x/python-ganttclient
Code Issues Proposed changes

terminology: no more plug-ins or queries. They are host filters and drivers.

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This commit is contained in:
Sandy Walsh
2011-05-05 18:09:11 -07:00
parent eb2efc7b40
commit fd94dbb2d5
2 changed files with 66 additions and 54 deletions
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76
nova/scheduler/query.py → nova/scheduler/host_filter.py
View File

@@ -14,14 +14,23 @@
# under the License.
"""
Query is a plug-in mechanism for requesting instance resources.
Three plug-ins are included: AllHosts, Flavor & JSON. AllHosts just
Host Filter is a driver mechanism for requesting instance resources.
Three drivers are included: AllHosts, Flavor & JSON. AllHosts just
returns the full, unfiltered list of hosts. Flavor is a hard coded
matching mechanism based on flavor criteria and JSON is an ad-hoc
query grammar.
filter grammar.
Note: These are hard filters. All capabilities used must be present
or the host will excluded. If you want soft filters use the weighting
Why JSON? The requests for instances may come in through the
REST interface from a user or a parent Zone.
Currently Flavors and/or InstanceTypes are used for
specifing the type of instance desired. Specific Nova users have
noted a need for a more expressive way of specifying instances.
Since we don't want to get into building full DSL this is a simple
form as an example of how this could be done. In reality, most
consumers will use the more rigid filters such as FlavorFilter.
Note: These are hard filters. All capabilities used must be present
or the host will be excluded. If you want soft filters use the weighting
mechanism which is intended for the more touchy-feely capabilities.
"""
@@ -32,36 +41,36 @@ from nova import flags
from nova import log as logging
from nova import utils
LOG = logging.getLogger('nova.scheduler.query')
LOG = logging.getLogger('nova.scheduler.host_filter')
FLAGS = flags.FLAGS
flags.DEFINE_string('default_query_engine',
'nova.scheduler.query.AllHostsQuery',
'Which query engine to use for filtering hosts.')
flags.DEFINE_string('default_host_filter_driver',
'nova.scheduler.host_filter.AllHostsFilter',
'Which driver to use for filtering hosts.')
class Query(object):
"""Base class for query plug-ins."""
class HostFilter(object):
"""Base class for host filter drivers."""
def instance_type_to_query(self, instance_type):
"""Convert instance_type into a query for most common use-case."""
def instance_type_to_filter(self, instance_type):
"""Convert instance_type into a filter for most common use-case."""
raise NotImplementedError()
def filter_hosts(self, zone_manager, query):
"""Return a list of hosts that fulfill the query."""
"""Return a list of hosts that fulfill the filter."""
raise NotImplementedError()
def _full_name(self):
"""module.classname of the Query object"""
"""module.classname of the filter driver"""
return "%s.%s" % (self.__module__, self.__class__.__name__)
class AllHostsQuery(Query):
"""NOP query plug-in. Returns all hosts in ZoneManager.
class AllHostsFilter(HostFilter):
"""NOP host filter driver. Returns all hosts in ZoneManager.
This essentially does what the old Scheduler+Chance used
to give us."""
def instance_type_to_query(self, instance_type):
def instance_type_to_filter(self, instance_type):
"""Return anything to prevent base-class from raising
exception."""
return (self._full_name(), instance_type)
@@ -72,10 +81,10 @@ class AllHostsQuery(Query):
for host, services in zone_manager.service_states.iteritems()]
class FlavorQuery(Query):
"""Query plug-in hard-coded to work with flavors."""
class FlavorFilter(HostFilter):
"""HostFilter driver hard-coded to work with flavors."""
def instance_type_to_query(self, instance_type):
def instance_type_to_filter(self, instance_type):
"""Use instance_type to filter hosts."""
return (self._full_name(), instance_type)
@@ -119,8 +128,9 @@ class FlavorQuery(Query):
#rxtx_cap = Column(Integer, nullable=False, default=0)
class JsonQuery(Query):
"""Query plug-in to allow simple JSON-based grammar for selecting hosts."""
class JsonFilter(HostFilter):
"""Host Filter driver to allow simple JSON-based grammar for
selecting hosts."""
def _equals(self, args):
"""First term is == all the other terms."""
@@ -204,8 +214,8 @@ class JsonQuery(Query):
'and': _and,
}
def instance_type_to_query(self, instance_type):
"""Convert instance_type into JSON query object."""
def instance_type_to_filter(self, instance_type):
"""Convert instance_type into JSON filter object."""
required_ram = instance_type['memory_mb']
required_disk = instance_type['local_gb']
query = ['and',
@@ -229,7 +239,7 @@ class JsonQuery(Query):
return None
return services
def _process_query(self, zone_manager, query, host, services):
def _process_filter(self, zone_manager, query, host, services):
"""Recursively parse the query structure."""
if len(query) == 0:
return True
@@ -238,7 +248,7 @@ class JsonQuery(Query):
cooked_args = []
for arg in query[1:]:
if isinstance(arg, list):
arg = self._process_query(zone_manager, arg, host, services)
arg = self._process_filter(zone_manager, arg, host, services)
elif isinstance(arg, basestring):
arg = self._parse_string(arg, host, services)
if arg != None:
@@ -247,11 +257,11 @@ class JsonQuery(Query):
return result
def filter_hosts(self, zone_manager, query):
"""Return a list of hosts that can fulfill query."""
"""Return a list of hosts that can fulfill filter."""
expanded = json.loads(query)
hosts = []
for host, services in zone_manager.service_states.iteritems():
r = self._process_query(zone_manager, expanded, host, services)
r = self._process_filter(zone_manager, expanded, host, services)
if isinstance(r, list):
r = True in r
if r:
@@ -259,7 +269,7 @@ class JsonQuery(Query):
return hosts
DRIVERS = [AllHostsQuery, FlavorQuery, JsonQuery]
DRIVERS = [AllHostsFilter, FlavorFilter, JsonFilter]
def choose_driver(driver_name=None):
@@ -267,10 +277,10 @@ def choose_driver(driver_name=None):
to have an authoritative list of what is permissible. This
function checks the driver name against a predefined set
of acceptable drivers."""
if not driver_name:
driver_name = FLAGS.default_query_engine
driver_name = FLAGS.default_host_filter_driver
for driver in DRIVERS:
if "%s.%s" % (driver.__module__, driver.__name__) == driver_name:
return driver()
raise exception.SchedulerQueryDriverNotFound(driver_name=driver_name)
raise exception.SchedulerHostFilterDriverNotFound(driver_name=driver_name)

44
nova/tests/test_query.py → nova/tests/test_host_filter.py
View File

@@ -13,7 +13,7 @@
# License for the specific language governing permissions and limitations
# under the License.
"""
Tests For Scheduler Query Drivers
Tests For Scheduler Host Filter Drivers.
"""
import json
@@ -21,7 +21,7 @@ import json
from nova import exception
from nova import flags
from nova import test
from nova.scheduler import query
from nova.scheduler import host_filter
FLAGS = flags.FLAGS
@@ -30,8 +30,8 @@ class FakeZoneManager:
pass
class QueryTestCase(test.TestCase):
"""Test case for query drivers."""
class HostFilterTestCase(test.TestCase):
"""Test case for host filter drivers."""
def _host_caps(self, multiplier):
# Returns host capabilities in the following way:
@@ -57,8 +57,9 @@ class QueryTestCase(test.TestCase):
'host_name-label': 'xs-%s' % multiplier}
def setUp(self):
self.old_flag = FLAGS.default_query_engine
FLAGS.default_query_engine = 'nova.scheduler.query.AllHostsQuery'
self.old_flag = FLAGS.default_host_filter_driver
FLAGS.default_host_filter_driver = \
'nova.scheduler.host_filter.AllHostsFilter'
self.instance_type = dict(name='tiny',
memory_mb=50,
vcpus=10,
@@ -75,37 +76,38 @@ class QueryTestCase(test.TestCase):
self.zone_manager.service_states = states
def tearDown(self):
FLAGS.default_query_engine = self.old_flag
FLAGS.default_host_filter_driver = self.old_flag
def test_choose_driver(self):
# Test default driver ...
driver = query.choose_driver()
driver = host_filter.choose_driver()
self.assertEquals(driver._full_name(),
'nova.scheduler.query.AllHostsQuery')
'nova.scheduler.host_filter.AllHostsFilter')
# Test valid driver ...
driver = query.choose_driver('nova.scheduler.query.FlavorQuery')
driver = host_filter.choose_driver(
'nova.scheduler.host_filter.FlavorFilter')
self.assertEquals(driver._full_name(),
'nova.scheduler.query.FlavorQuery')
'nova.scheduler.host_filter.FlavorFilter')
# Test invalid driver ...
try:
query.choose_driver('does not exist')
host_filter.choose_driver('does not exist')
self.fail("Should not find driver")
except exception.SchedulerQueryDriverNotFound:
except exception.SchedulerHostFilterDriverNotFound:
pass
def test_all_host_driver(self):
driver = query.AllHostsQuery()
cooked = driver.instance_type_to_query(self.instance_type)
driver = host_filter.AllHostsFilter()
cooked = driver.instance_type_to_filter(self.instance_type)
hosts = driver.filter_hosts(self.zone_manager, cooked)
self.assertEquals(10, len(hosts))
for host, capabilities in hosts:
self.assertTrue(host.startswith('host'))
def test_flavor_driver(self):
driver = query.FlavorQuery()
driver = host_filter.FlavorFilter()
# filter all hosts that can support 50 ram and 500 disk
name, cooked = driver.instance_type_to_query(self.instance_type)
self.assertEquals('nova.scheduler.query.FlavorQuery', name)
name, cooked = driver.instance_type_to_filter(self.instance_type)
self.assertEquals('nova.scheduler.host_filter.FlavorFilter', name)
hosts = driver.filter_hosts(self.zone_manager, cooked)
self.assertEquals(6, len(hosts))
just_hosts = [host for host, caps in hosts]
@@ -114,10 +116,10 @@ class QueryTestCase(test.TestCase):
self.assertEquals('host10', just_hosts[5])
def test_json_driver(self):
driver = query.JsonQuery()
driver = host_filter.JsonFilter()
# filter all hosts that can support 50 ram and 500 disk
name, cooked = driver.instance_type_to_query(self.instance_type)
self.assertEquals('nova.scheduler.query.JsonQuery', name)
name, cooked = driver.instance_type_to_filter(self.instance_type)
self.assertEquals('nova.scheduler.host_filter.JsonFilter', name)
hosts = driver.filter_hosts(self.zone_manager, cooked)
self.assertEquals(6, len(hosts))
just_hosts = [host for host, caps in hosts]