From ca5294a801104fa5ea859b7b3762ba2f4c5e607b Mon Sep 17 00:00:00 2001
From: Artem Osadchyi <aosadchiy@maprtech.com>
Date: Wed, 30 Sep 2015 17:25:22 +0300
Subject: [PATCH] Removed redundant metaclass declarations in MapR plugin

Change-Id: Ifad8f7521be49c5564f43e6df78f2d49fb753ba0
Implements: blueprint mapr-refactor-singleton
---
 sahara/plugins/mapr/domain/service.py                | 12 +++---------
 sahara/plugins/mapr/services/drill/drill.py          |  7 -------
 sahara/plugins/mapr/services/flume/flume.py          |  3 ---
 sahara/plugins/mapr/services/hbase/hbase.py          |  6 ------
 sahara/plugins/mapr/services/hive/hive.py            |  3 ---
 sahara/plugins/mapr/services/httpfs/httpfs.py        |  3 ---
 sahara/plugins/mapr/services/hue/hue.py              |  5 -----
 sahara/plugins/mapr/services/impala/impala.py        |  3 ---
 sahara/plugins/mapr/services/mahout/mahout.py        |  5 -----
 .../plugins/mapr/services/management/management.py   |  3 ---
 sahara/plugins/mapr/services/mapreduce/mapreduce.py  |  3 ---
 sahara/plugins/mapr/services/maprfs/maprfs.py        |  2 --
 sahara/plugins/mapr/services/mysql/mysql.py          |  1 -
 sahara/plugins/mapr/services/oozie/oozie.py          |  4 ----
 sahara/plugins/mapr/services/pig/pig.py              |  5 -----
 sahara/plugins/mapr/services/spark/spark.py          |  1 -
 sahara/plugins/mapr/services/sqoop/sqoop2.py         |  3 ---
 sahara/plugins/mapr/services/swift/swift.py          |  2 --
 sahara/plugins/mapr/services/yarn/yarn.py            |  5 -----
 sahara/plugins/mapr/util/general.py                  | 11 +++++++++++
 20 files changed, 14 insertions(+), 73 deletions(-)

diff --git a/sahara/plugins/mapr/domain/service.py b/sahara/plugins/mapr/domain/service.py
index 6e1abd59..8f30a02c 100644
--- a/sahara/plugins/mapr/domain/service.py
+++ b/sahara/plugins/mapr/domain/service.py
@@ -14,11 +14,13 @@
 
 
 from oslo_serialization import jsonutils as json
+import six
 
 from sahara import context
 import sahara.exceptions as e
 from sahara.i18n import _
 import sahara.plugins.exceptions as ex
+from sahara.plugins.mapr.util import general as g
 from sahara.plugins.mapr.util import service_utils as su
 import sahara.plugins.provisioning as p
 from sahara.utils import files as files
@@ -26,6 +28,7 @@ from sahara.utils import files as files
 _INSTALL_PACKAGES_TIMEOUT = 3600
 
 
+@six.add_metaclass(g.Singleton)
 class Service(object):
     def __init__(self):
         self._name = None
@@ -219,12 +222,3 @@ class Service(object):
 
     def post_configure_sh(self, cluster_context, instances):
         pass
-
-
-class Single(type):
-    _instances = {}
-
-    def __call__(cls, *args, **kwargs):
-        if cls not in cls._instances:
-            cls._instances[cls] = super(Single, cls).__call__(*args, **kwargs)
-        return cls._instances[cls]
diff --git a/sahara/plugins/mapr/services/drill/drill.py b/sahara/plugins/mapr/services/drill/drill.py
index d6560030..c39604dc 100644
--- a/sahara/plugins/mapr/services/drill/drill.py
+++ b/sahara/plugins/mapr/services/drill/drill.py
@@ -13,8 +13,6 @@
 # under the License.
 
 
-import six
-
 import sahara.plugins.mapr.domain.node_process as np
 import sahara.plugins.mapr.domain.service as s
 import sahara.plugins.mapr.util.commands as cmd
@@ -29,7 +27,6 @@ DRILL = np.NodeProcess(
 )
 
 
-@six.add_metaclass(s.Single)
 class Drill(s.Service):
     def __init__(self):
         super(Drill, self).__init__()
@@ -51,28 +48,24 @@ class Drill(s.Service):
             cmd.re_configure_sh(instance, cluster_context)
 
 
-@six.add_metaclass(s.Single)
 class DrillV07(Drill):
     def __init__(self):
         super(DrillV07, self).__init__()
         self._version = '0.7'
 
 
-@six.add_metaclass(s.Single)
 class DrillV08(Drill):
     def __init__(self):
         super(DrillV08, self).__init__()
         self._version = '0.8'
 
 
-@six.add_metaclass(s.Single)
 class DrillV09(Drill):
     def __init__(self):
         super(DrillV09, self).__init__()
         self._version = '0.9'
 
 
-@six.add_metaclass(s.Single)
 class DrillV11(Drill):
     def __init__(self):
         super(DrillV11, self).__init__()
diff --git a/sahara/plugins/mapr/services/flume/flume.py b/sahara/plugins/mapr/services/flume/flume.py
index de4b30e1..8844a63f 100755
--- a/sahara/plugins/mapr/services/flume/flume.py
+++ b/sahara/plugins/mapr/services/flume/flume.py
@@ -13,8 +13,6 @@
 # under the License.
 
 
-import six
-
 import sahara.plugins.mapr.domain.node_process as np
 import sahara.plugins.mapr.domain.service as s
 import sahara.plugins.mapr.util.validation_utils as vu
@@ -28,7 +26,6 @@ FLUME = np.NodeProcess(
 )
 
 
-@six.add_metaclass(s.Single)
 class Flume(s.Service):
     def __init__(self):
         super(Flume, self).__init__()
diff --git a/sahara/plugins/mapr/services/hbase/hbase.py b/sahara/plugins/mapr/services/hbase/hbase.py
index e1bc2a10..fe93f009 100644
--- a/sahara/plugins/mapr/services/hbase/hbase.py
+++ b/sahara/plugins/mapr/services/hbase/hbase.py
@@ -13,8 +13,6 @@
 # under the License.
 
 
-import six
-
 import sahara.plugins.mapr.domain.configuration_file as bcf
 import sahara.plugins.mapr.domain.node_process as np
 import sahara.plugins.mapr.domain.service as s
@@ -75,7 +73,6 @@ class HBase(s.Service):
         return [hbase_site]
 
 
-@six.add_metaclass(s.Single)
 class HBaseV094(HBase):
     def __init__(self):
         super(HBaseV094, self).__init__()
@@ -83,7 +80,6 @@ class HBaseV094(HBase):
         self._dependencies = [('mapr-hbase', self.version)]
 
 
-@six.add_metaclass(s.Single)
 class HBaseV0987(HBase):
     def __init__(self):
         super(HBaseV0987, self).__init__()
@@ -91,7 +87,6 @@ class HBaseV0987(HBase):
         self._dependencies = [('mapr-hbase', self.version)]
 
 
-@six.add_metaclass(s.Single)
 class HBaseV0989(HBase):
     def __init__(self):
         super(HBaseV0989, self).__init__()
@@ -103,7 +98,6 @@ class HBaseV0989(HBase):
         )
 
 
-@six.add_metaclass(s.Single)
 class HBaseV09812(HBase):
     def __init__(self):
         super(HBaseV09812, self).__init__()
diff --git a/sahara/plugins/mapr/services/hive/hive.py b/sahara/plugins/mapr/services/hive/hive.py
index 7c5c7866..46d7238f 100644
--- a/sahara/plugins/mapr/services/hive/hive.py
+++ b/sahara/plugins/mapr/services/hive/hive.py
@@ -14,7 +14,6 @@
 
 
 from oslo_log import log as logging
-import six
 
 import sahara.plugins.mapr.domain.configuration_file as bcf
 import sahara.plugins.mapr.domain.node_process as np
@@ -121,7 +120,6 @@ class Hive(s.Service):
         return self.SCHEMA_PATH_TEMPLATE % args
 
 
-@six.add_metaclass(s.Single)
 class HiveV013(Hive):
     def __init__(self):
         super(HiveV013, self).__init__()
@@ -129,7 +127,6 @@ class HiveV013(Hive):
         self._dependencies = [('mapr-hive', self.version)]
 
 
-@six.add_metaclass(s.Single)
 class HiveV10(Hive):
     def __init__(self):
         super(HiveV10, self).__init__()
diff --git a/sahara/plugins/mapr/services/httpfs/httpfs.py b/sahara/plugins/mapr/services/httpfs/httpfs.py
index 74f51867..b896c3d4 100644
--- a/sahara/plugins/mapr/services/httpfs/httpfs.py
+++ b/sahara/plugins/mapr/services/httpfs/httpfs.py
@@ -13,8 +13,6 @@
 # under the License.
 
 
-import six
-
 import sahara.plugins.mapr.domain.node_process as np
 import sahara.plugins.mapr.domain.service as s
 import sahara.plugins.mapr.util.commands as cmd
@@ -29,7 +27,6 @@ HTTP_FS = np.NodeProcess(
 )
 
 
-@six.add_metaclass(s.Single)
 class HttpFS(s.Service):
     def __init__(self):
         super(HttpFS, self).__init__()
diff --git a/sahara/plugins/mapr/services/hue/hue.py b/sahara/plugins/mapr/services/hue/hue.py
index 450ecf4b..ffdd7b9a 100755
--- a/sahara/plugins/mapr/services/hue/hue.py
+++ b/sahara/plugins/mapr/services/hue/hue.py
@@ -18,7 +18,6 @@ import random
 import string
 
 from oslo_log import log as logging
-import six
 
 import sahara.plugins.mapr.domain.configuration_file as bcf
 import sahara.plugins.mapr.domain.node_process as np
@@ -53,7 +52,6 @@ HUE_LIVY = np.NodeProcess(
 )
 
 
-@six.add_metaclass(s.Single)
 class Hue(s.Service):
     def __init__(self):
         super(Hue, self).__init__()
@@ -208,21 +206,18 @@ class Hue(s.Service):
         return ''.join(generator.choice(ascii_alphanum) for _ in range(length))
 
 
-@six.add_metaclass(s.Single)
 class HueV360(Hue):
     def __init__(self):
         super(HueV360, self).__init__()
         self._version = '3.6.0'
 
 
-@six.add_metaclass(s.Single)
 class HueV370(Hue):
     def __init__(self):
         super(HueV370, self).__init__()
         self._version = '3.7.0'
 
 
-@six.add_metaclass(s.Single)
 class HueV381(Hue):
     def __init__(self):
         super(HueV381, self).__init__()
diff --git a/sahara/plugins/mapr/services/impala/impala.py b/sahara/plugins/mapr/services/impala/impala.py
index 98f77c90..cdc61cce 100755
--- a/sahara/plugins/mapr/services/impala/impala.py
+++ b/sahara/plugins/mapr/services/impala/impala.py
@@ -13,8 +13,6 @@
 # under the License.
 
 
-import six
-
 import sahara.plugins.mapr.domain.configuration_file as bcf
 import sahara.plugins.mapr.domain.node_process as np
 import sahara.plugins.mapr.domain.service as s
@@ -76,7 +74,6 @@ class Impala(s.Service):
             cmd.chown(instance, 'mapr:mapr', self.service_dir(cluster_context))
 
 
-@six.add_metaclass(s.Single)
 class ImpalaV141(Impala):
     def __init__(self):
         super(ImpalaV141, self).__init__()
diff --git a/sahara/plugins/mapr/services/mahout/mahout.py b/sahara/plugins/mapr/services/mahout/mahout.py
index aec89636..b9712294 100644
--- a/sahara/plugins/mapr/services/mahout/mahout.py
+++ b/sahara/plugins/mapr/services/mahout/mahout.py
@@ -13,8 +13,6 @@
 # under the License.
 
 
-import six
-
 import sahara.plugins.mapr.domain.node_process as np
 import sahara.plugins.mapr.domain.service as s
 import sahara.plugins.mapr.util.validation_utils as vu
@@ -27,7 +25,6 @@ MAHOUT = np.NodeProcess(
 )
 
 
-@six.add_metaclass(s.Single)
 class Mahout(s.Service):
     def __init__(self):
         super(Mahout, self).__init__()
@@ -37,14 +34,12 @@ class Mahout(s.Service):
         self._validation_rules = [vu.at_least(1, MAHOUT)]
 
 
-@six.add_metaclass(s.Single)
 class MahoutV09(Mahout):
     def __init__(self):
         super(MahoutV09, self).__init__()
         self._version = '0.9'
 
 
-@six.add_metaclass(s.Single)
 class MahoutV010(Mahout):
     def __init__(self):
         super(MahoutV010, self).__init__()
diff --git a/sahara/plugins/mapr/services/management/management.py b/sahara/plugins/mapr/services/management/management.py
index 0ed08f92..a445e1c7 100644
--- a/sahara/plugins/mapr/services/management/management.py
+++ b/sahara/plugins/mapr/services/management/management.py
@@ -13,8 +13,6 @@
 # under the License.
 
 
-import six
-
 import sahara.plugins.mapr.domain.node_process as np
 import sahara.plugins.mapr.domain.service as s
 import sahara.plugins.mapr.util.validation_utils as vu
@@ -44,7 +42,6 @@ METRICS = np.NodeProcess(
 )
 
 
-@six.add_metaclass(s.Single)
 class Management(s.Service):
     def __init__(self):
         super(Management, self).__init__()
diff --git a/sahara/plugins/mapr/services/mapreduce/mapreduce.py b/sahara/plugins/mapr/services/mapreduce/mapreduce.py
index d01d1f3e..c2b1b6e8 100644
--- a/sahara/plugins/mapr/services/mapreduce/mapreduce.py
+++ b/sahara/plugins/mapr/services/mapreduce/mapreduce.py
@@ -12,8 +12,6 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import six
-
 import sahara.plugins.mapr.domain.configuration_file as bcf
 import sahara.plugins.mapr.domain.node_process as np
 import sahara.plugins.mapr.domain.service as s
@@ -42,7 +40,6 @@ JACKSON_MAPPER_ASL = ('plugins/mapr/services/swift/resources/'
                       'jackson-mapper-asl-1.9.13.jar')
 
 
-@six.add_metaclass(s.Single)
 class MapReduce(s.Service):
     cluster_mode = 'classic'
 
diff --git a/sahara/plugins/mapr/services/maprfs/maprfs.py b/sahara/plugins/mapr/services/maprfs/maprfs.py
index bea23fe3..2b2d5a7a 100644
--- a/sahara/plugins/mapr/services/maprfs/maprfs.py
+++ b/sahara/plugins/mapr/services/maprfs/maprfs.py
@@ -14,7 +14,6 @@
 
 
 from oslo_log import log as logging
-import six
 
 from sahara import context
 from sahara.i18n import _
@@ -50,7 +49,6 @@ NFS = np.NodeProcess(
 )
 
 
-@six.add_metaclass(s.Single)
 class MapRFS(s.Service):
     _CREATE_DISK_LIST = 'plugins/mapr/resources/create_disk_list_file.sh'
     _DISK_SETUP_CMD = '/opt/mapr/server/disksetup -F /tmp/disk.list'
diff --git a/sahara/plugins/mapr/services/mysql/mysql.py b/sahara/plugins/mapr/services/mysql/mysql.py
index 578ab102..e4eae915 100644
--- a/sahara/plugins/mapr/services/mysql/mysql.py
+++ b/sahara/plugins/mapr/services/mysql/mysql.py
@@ -30,7 +30,6 @@ LOG = logging.getLogger(__name__)
 db_spec = c.namedtuple('DatabaseSpec', ['db_name', 'user', 'password'])
 
 
-@six.add_metaclass(s.Single)
 class MySQL(s.Service):
     METRICS_SPECS = db_spec('metrics', 'maprmetrics', 'mapr')
     HUE_SPECS = db_spec('hue', 'maprhue', 'mapr')
diff --git a/sahara/plugins/mapr/services/oozie/oozie.py b/sahara/plugins/mapr/services/oozie/oozie.py
index 22e87246..eefda6d6 100644
--- a/sahara/plugins/mapr/services/oozie/oozie.py
+++ b/sahara/plugins/mapr/services/oozie/oozie.py
@@ -14,7 +14,6 @@
 
 
 from oslo_log import log as logging
-import six
 
 import sahara.plugins.mapr.domain.configuration_file as bcf
 import sahara.plugins.mapr.domain.node_process as np
@@ -34,7 +33,6 @@ OOZIE = np.NodeProcess(
 )
 
 
-@six.add_metaclass(s.Single)
 class Oozie(s.Service):
     def __init__(self):
         super(Oozie, self).__init__()
@@ -116,7 +114,6 @@ class Oozie(s.Service):
         OOZIE.start(instances)
 
 
-@six.add_metaclass(s.Single)
 class OozieV401(Oozie):
     def __init__(self):
         super(OozieV401, self).__init__()
@@ -124,7 +121,6 @@ class OozieV401(Oozie):
         self._dependencies = [('mapr-oozie-internal', self.version)]
 
 
-@six.add_metaclass(s.Single)
 class OozieV410(Oozie):
     def __init__(self):
         super(OozieV410, self).__init__()
diff --git a/sahara/plugins/mapr/services/pig/pig.py b/sahara/plugins/mapr/services/pig/pig.py
index 8fd69438..88d03c59 100644
--- a/sahara/plugins/mapr/services/pig/pig.py
+++ b/sahara/plugins/mapr/services/pig/pig.py
@@ -13,8 +13,6 @@
 # under the License.
 
 
-import six
-
 import sahara.plugins.mapr.domain.node_process as np
 import sahara.plugins.mapr.domain.service as s
 import sahara.plugins.mapr.util.validation_utils as vu
@@ -27,7 +25,6 @@ PIG = np.NodeProcess(
 )
 
 
-@six.add_metaclass(s.Single)
 class Pig(s.Service):
     def __init__(self):
         super(Pig, self).__init__()
@@ -37,14 +34,12 @@ class Pig(s.Service):
         self._validation_rules = [vu.at_least(1, PIG)]
 
 
-@six.add_metaclass(s.Single)
 class PigV013(Pig):
     def __init__(self):
         super(PigV013, self).__init__()
         self._version = '0.13'
 
 
-@six.add_metaclass(s.Single)
 class PigV014(Pig):
     def __init__(self):
         super(PigV014, self).__init__()
diff --git a/sahara/plugins/mapr/services/spark/spark.py b/sahara/plugins/mapr/services/spark/spark.py
index 26f19ec0..df83abb1 100755
--- a/sahara/plugins/mapr/services/spark/spark.py
+++ b/sahara/plugins/mapr/services/spark/spark.py
@@ -74,7 +74,6 @@ SPARK_SLAVE = SparkWorker(
 )
 
 
-@six.add_metaclass(s.Single)
 class Spark(s.Service):
     def __init__(self):
         super(Spark, self).__init__()
diff --git a/sahara/plugins/mapr/services/sqoop/sqoop2.py b/sahara/plugins/mapr/services/sqoop/sqoop2.py
index a345a11f..51df0f04 100755
--- a/sahara/plugins/mapr/services/sqoop/sqoop2.py
+++ b/sahara/plugins/mapr/services/sqoop/sqoop2.py
@@ -13,8 +13,6 @@
 # under the License.
 
 
-import six
-
 import sahara.plugins.mapr.domain.node_process as np
 import sahara.plugins.mapr.domain.service as s
 import sahara.plugins.mapr.util.commands as cmd
@@ -34,7 +32,6 @@ SQOOP_2_CLIENT = np.NodeProcess(
 )
 
 
-@six.add_metaclass(s.Single)
 class Sqoop2(s.Service):
     def __init__(self):
         super(Sqoop2, self).__init__()
diff --git a/sahara/plugins/mapr/services/swift/swift.py b/sahara/plugins/mapr/services/swift/swift.py
index 8a274e0f..6446a922 100644
--- a/sahara/plugins/mapr/services/swift/swift.py
+++ b/sahara/plugins/mapr/services/swift/swift.py
@@ -14,7 +14,6 @@
 
 
 from oslo_log import log as logging
-import six
 
 import sahara.plugins.mapr.domain.service as s
 import sahara.plugins.mapr.services.maprfs.maprfs as maprfs
@@ -23,7 +22,6 @@ import sahara.utils.files as f
 LOG = logging.getLogger(__name__)
 
 
-@six.add_metaclass(s.Single)
 class Swift(s.Service):
     HADOOP_SWIFT_JAR = ('plugins/mapr/services/swift/'
                         'resources/hadoop-swift-latest.jar')
diff --git a/sahara/plugins/mapr/services/yarn/yarn.py b/sahara/plugins/mapr/services/yarn/yarn.py
index 028ad926..5a646101 100644
--- a/sahara/plugins/mapr/services/yarn/yarn.py
+++ b/sahara/plugins/mapr/services/yarn/yarn.py
@@ -13,8 +13,6 @@
 # under the License.
 
 
-import six
-
 import sahara.plugins.mapr.domain.configuration_file as bcf
 import sahara.plugins.mapr.domain.node_process as np
 import sahara.plugins.mapr.domain.service as s
@@ -111,7 +109,6 @@ class YARN(s.Service):
         return template % file_name
 
 
-@six.add_metaclass(s.Single)
 class YARNv241(YARN):
     def __init__(self):
         super(YARNv241, self).__init__()
@@ -123,7 +120,6 @@ class YARNv241(YARN):
         ]
 
 
-@six.add_metaclass(s.Single)
 class YARNv251(YARN):
     def __init__(self):
         super(YARNv251, self).__init__()
@@ -135,7 +131,6 @@ class YARNv251(YARN):
         ]
 
 
-@six.add_metaclass(s.Single)
 class YARNv270(YARN):
     def __init__(self):
         super(YARNv270, self).__init__()
diff --git a/sahara/plugins/mapr/util/general.py b/sahara/plugins/mapr/util/general.py
index 9249e15d..7edc8dda 100644
--- a/sahara/plugins/mapr/util/general.py
+++ b/sahara/plugins/mapr/util/general.py
@@ -190,3 +190,14 @@ def download(remote, url, output=None, run_as=None):
     args = {'url': url, 'output': '-O %s' % output if output else ''}
     command = _run_as(run_as, 'wget -q %(output)s %(url)s' % args)
     remote.execute_command(command, timeout=600)
+
+
+class Singleton(type):
+    instances = {}
+
+    def __call__(cls, *args, **kwargs):
+        if cls not in cls.instances:
+            new_instance = super(Singleton, cls).__call__(*args, **kwargs)
+            cls.instances[cls] = new_instance
+
+        return cls.instances[cls]