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__init__.py
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__init__.py
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# Copyright European Organization for Nuclear Research (CERN) since 2012
#
# 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.
from typing import TYPE_CHECKING, Optional, TypeVar
from sqlalchemy.sql.expression import bindparam, text
if TYPE_CHECKING:
from sqlalchemy.orm import Session
from sqlalchemy.orm.query import RowReturningQuery
from sqlalchemy.sql.selectable import Select
Q = TypeVar('Q', RowReturningQuery, Select)
def filter_thread_work(
session: "Session",
query: "Q",
total_threads: Optional[int],
thread_id: Optional[int],
hash_variable: Optional[str] = None
) -> "Q":
""" Filters a query to partition thread workloads based on the thread id and total number of threads """
if thread_id is not None and total_threads is not None and (total_threads - 1) > 0:
if session.bind.dialect.name == 'oracle':
bindparams = [bindparam('thread_id', thread_id), bindparam('total_threads', total_threads - 1)]
if not hash_variable:
query = query.filter(text('ORA_HASH(id, :total_threads) = :thread_id').bindparams(*bindparams))
else:
query = query.filter(text('ORA_HASH(%s, :total_threads) = :thread_id' % (hash_variable)).bindparams(*bindparams))
elif session.bind.dialect.name == 'mysql':
if not hash_variable:
query = query.filter(text('mod(md5(id), %s) = %s' % (total_threads, thread_id)))
else:
query = query.filter(text('mod(md5(%s), %s) = %s' % (hash_variable, total_threads, thread_id)))
elif session.bind.dialect.name == 'postgresql':
if not hash_variable:
query = query.filter(text('mod(abs((\'x\'||md5(id::text))::bit(32)::bigint), %s) = %s' % (total_threads, thread_id)))
else:
query = query.filter(text('mod(abs((\'x\'||md5(%s::text))::bit(32)::bigint), %s) = %s' % (hash_variable, total_threads, thread_id)))
return query