Convert alarm timestamp to PrecisionTimestamp

Before the timestamps for alarm are stored in a datetime
In mysql, datetimes have only second precision, and the datetimes are
rounded.

This patch, change the Datetime by the PrecisionTimestamp Column Type, like
the sample and the event timestamps that demand the same precision.

Change-Id: Iad10c621b276fc40b9965d01bc460bcc834b473a

ceilometer/storage/sqlalchemy/migrate_repo/versions/025_alarm_use_floatingprecision.py

@@ -0,0 +1,82 @@
+# -*- encoding: utf-8 -*-
+#
+# Copyright © 2013 eNovance SAS <licensing@enovance.com>
+#
+# Author: Mehdi Abaakouk <mehdi.abaakouk@enovance.com>
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import sqlalchemy as sa
+
+from ceilometer.storage.sqlalchemy import models
+
+
+def _paged(query, size):
+    offset = 0
+    while True:
+        page = query.offset(offset).limit(size).execute()
+        if page.rowcount <= 0:
+            # There are no more rows
+            break
+        for row in page:
+            yield row
+        offset += size
+
+
+def _convert_data_type(table, col, from_t, to_t, pk_attr='id'):
+    temp_col_n = 'convert_data_type_temp_col'
+    # Override column we're going to convert with from_t, since the type we're
+    # replacing could be custom and we need to tell SQLALchemy how to perform
+    # CRUD operations with it.
+    table = sa.Table(table.name, table.metadata, sa.Column(col, from_t),
+                     extend_existing=True)
+    sa.Column(temp_col_n, to_t).create(table)
+
+    key_attr = getattr(table.c, pk_attr)
+    orig_col = getattr(table.c, col)
+    new_col = getattr(table.c, temp_col_n)
+
+    query = sa.select([key_attr, orig_col])
+    for key, value in _paged(query, 1000):
+        table.update().where(key_attr == key)\
+            .values({temp_col_n: value}).execute()
+
+    orig_col.drop()
+    new_col.alter(name=col)
+
+
+to_convert = [
+    ('alarm', 'timestamp', 'id'),
+    ('alarm', 'state_timestamp', 'id'),
+    ('alarm_history', 'timestamp', 'alarm_id'),
+]
+
+
+def upgrade(migrate_engine):
+    if migrate_engine.name == 'mysql':
+        meta = sa.MetaData(bind=migrate_engine)
+        for table_name, col_name, pk_attr in to_convert:
+            table = sa.Table(table_name, meta, autoload=True)
+            _convert_data_type(table, col_name, sa.DateTime(),
+                               models.PreciseTimestamp(),
+                               pk_attr=pk_attr)
+
+
+def downgrade(migrate_engine):
+    if migrate_engine.name == 'mysql':
+        meta = sa.MetaData(bind=migrate_engine)
+        for table_name, col_name, pk_attr in to_convert:
+            table = sa.Table(table_name, meta, autoload=True)
+            _convert_data_type(table, col_name, models.PreciseTimestamp(),
+                               sa.DateTime(),
+                               pk_attr=pk_attr)

ceilometer/storage/sqlalchemy/models.py

@@ -22,7 +22,7 @@ import json
 import urlparse
 
 from oslo.config import cfg
-from sqlalchemy import Column, Integer, String, Table, ForeignKey, DateTime, \
+from sqlalchemy import Column, Integer, String, Table, ForeignKey, \
     Index, UniqueConstraint, BigInteger
 from sqlalchemy import Float, Boolean, Text
 from sqlalchemy.dialects.mysql import DECIMAL
@@ -265,13 +265,13 @@ class Alarm(Base):
     name = Column(Text)
     type = Column(String(50))
     description = Column(Text)
-    timestamp = Column(DateTime, default=timeutils.utcnow)
+    timestamp = Column(PreciseTimestamp, default=timeutils.utcnow)
 
     user_id = Column(String(255), ForeignKey('user.id'))
     project_id = Column(String(255), ForeignKey('project.id'))
 
     state = Column(String(255))
-    state_timestamp = Column(DateTime, default=timeutils.utcnow)
+    state_timestamp = Column(PreciseTimestamp, default=timeutils.utcnow)
 
     ok_actions = Column(JSONEncodedDict)
     alarm_actions = Column(JSONEncodedDict)
@@ -294,7 +294,7 @@ class AlarmChange(Base):
     user_id = Column(String(255), ForeignKey('user.id'))
     type = Column(String(20))
     detail = Column(Text)
-    timestamp = Column(DateTime, default=timeutils.utcnow)
+    timestamp = Column(PreciseTimestamp, default=timeutils.utcnow)
 
 
 class EventType(Base):