89 lines
2.9 KiB
Python
89 lines
2.9 KiB
Python
# Copyright 2012 Anton Beloglazov
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from contracts import contract
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from sqlalchemy import *
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from sqlalchemy.engine.base import Connection
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class Database(object):
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""" A class representing the database, where fields are tables.
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"""
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@contract(connection=Connection, vms=Table, vm_resource_usage=Table)
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def __init__(self, connection, vms, vm_resource_usage):
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""" Initialize the database.
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:param connection: A database connection table.
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:param vms: The vms table.
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:param vm_resource_usage: The vm_resource_usage table.
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"""
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self.connection = connection
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self.vms = vms
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self.vm_resource_usage = vm_resource_usage
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@contract
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def select_cpu_mhz_for_vm(self, uuid, n):
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""" Select n last values of CPU MHz for a VM UUID.
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:param uuid: The UUID of a VM.
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:type uuid: str[36]
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:param n: The number of last values to select.
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:type n: int,>0
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:return: The list of n last CPU Mhz values.
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:rtype: list(int)
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"""
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sel = select([self.vm_resource_usage.c.cpu_mhz]). \
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where(and_(
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self.vms.c.id == self.vm_resource_usage.c.vm_id,
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self.vms.c.uuid == uuid)). \
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order_by(self.vm_resource_usage.c.id.asc()). \
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limit(n)
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res = self.connection.execute(sel).fetchall()
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return [x[0] for x in res]
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@contract
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def select_vm_id(self, uuid):
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""" Select the ID of a VM by the VM UUID, or insert a new record.
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:param uuid: The UUID of a VM.
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:type uuid: str[36]
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:return: The ID of the VM.
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:rtype: int
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"""
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sel = select([self.vms.c.id]).where(self.vms.c.uuid == uuid)
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row = self.connection.execute(sel).fetchone()
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if row == None:
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return self.vms.insert().execute(uuid=uuid).inserted_primary_key[0]
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else:
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return row['id']
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@contract
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def insert_cpu_mhz(self, data):
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""" Insert a set of CPU MHz values for a set of VMs.
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:param data: A dictionary of VM UUIDs and CPU MHz values.
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:type data: dict(str : int)
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"""
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if data:
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query = []
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for uuid, cpu_mhz in data.items():
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vm_id = self.select_vm_id(uuid)
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query.append({'vm_id': vm_id,
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'cpu_mhz': cpu_mhz})
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self.vm_resource_usage.insert().execute(query)
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