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rse_expression_parser.py
460 lines (384 loc) · 15 KB
/
rse_expression_parser.py
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# -*- coding: utf-8 -*-
# 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.
import abc
import re
from hashlib import sha256
from typing import TYPE_CHECKING
from dogpile.cache.api import NoValue
from rucio.common.cache import make_region_memcached
from rucio.common.exception import InvalidRSEExpression, RSEWriteBlocked
from rucio.core.rse import list_rses, get_rses_with_attribute, get_rse_attribute
from rucio.db.sqla.session import transactional_session
if TYPE_CHECKING:
from sqlalchemy.orm import Session
DEFAULT_RSE_ATTRIBUTE = r'([A-Za-z0-9]+([_-][A-Za-z0-9]+)*)'
RSE_ATTRIBUTE = r'([A-Za-z0-9\._-]+[=<>][A-Za-z0-9_-]+)'
PRIMITIVE = r'(\(*(%s|%s|%s)\)*)' % (RSE_ATTRIBUTE, DEFAULT_RSE_ATTRIBUTE, r'\*')
UNION = r'(\|%s)' % (PRIMITIVE)
INTERSECTION = r'(\&%s)' % (PRIMITIVE)
COMPLEMENT = r'(\\%s)' % (PRIMITIVE)
PATTERN = r'^%s(%s|%s|%s)*' % (PRIMITIVE, UNION, INTERSECTION, COMPLEMENT)
REGION = make_region_memcached(expiration_time=600)
@transactional_session
def parse_expression(expression, filter_=None, *, session: "Session"):
"""
Parse a RSE expression and return the list of RSE dictionaries.
:param expression: RSE expression, e.g: 'CERN|BNL'.
:param filter_: Availability filter (dictionary) used for the RSEs. e.g.: {'availability_write': True}
:param session: Database session in use.
:returns: A list of rse dictionaries.
:raises: InvalidRSEExpression, RSENotFound, RSEWriteBlocked
"""
result = REGION.get(sha256(expression.encode()).hexdigest())
if type(result) is NoValue:
# Evaluate the correctness of the parentheses
parantheses_open_count = 0
parantheses_close_count = 0
for char in expression:
if (char == '('):
parantheses_open_count += 1
elif (char == ')'):
parantheses_close_count += 1
if (parantheses_close_count > parantheses_open_count):
raise InvalidRSEExpression('Problem with parantheses.')
if (parantheses_open_count != parantheses_close_count):
raise InvalidRSEExpression('Problem with parantheses.')
# Check the expression pattern
match = re.match(PATTERN, expression)
if match is None:
raise InvalidRSEExpression('Expression does not comply to RSE Expression syntax')
else:
if match.group() != expression:
raise InvalidRSEExpression('Expression does not comply to RSE Expression syntax')
result_tuple = __resolve_term_expression(expression)[0].resolve_elements(session=session)
# result_tuple = ([rse_ids], {rse_id: {rse_info}})
result = []
for rse in list(result_tuple[0]):
result.append(result_tuple[1][rse])
REGION.set(sha256(expression.encode()).hexdigest(), result)
# Filter for VO
vo_result = []
if filter_ and filter_.get('vo'):
filter_ = filter_.copy() # Make a copy so we can pop('vo') without affecting the object `filter` outside this function
vo = filter_.pop('vo')
for rse in result:
if rse.get('vo') == vo:
vo_result.append(rse)
else:
vo_result = result
if not vo_result:
raise InvalidRSEExpression('RSE Expression resulted in an empty set.')
# Filter
final_result = []
if filter_:
for rse in vo_result:
if filter_.get('availability_write', False):
if rse.get('availability_write'):
final_result.append(rse)
if not final_result:
raise RSEWriteBlocked('RSE excluded; not available for writing.')
else:
final_result = vo_result
# final_result = [{rse-info}]
return final_result
def __resolve_term_expression(expression):
"""
Resolves a Term Expression and returns an object of type BaseExpressionElement
:param subexpression: String of the term expression.
:returns: Tuple of BaseExpressionElement, term Expression string
"""
left_term = None
operator = None
original_expression = expression
while True:
if len(expression) == 0:
return (left_term, original_expression)
elif expression[0] == "(":
if left_term is None:
left_term, termexpression = __resolve_term_expression(__extract_term(expression))
expression = expression[len(termexpression) + 2:]
continue
else:
right_term, termexpression = __resolve_term_expression(__extract_term(expression))
expression = expression[len(termexpression) + 2:]
operator.set_left_term(left_term)
operator.set_right_term(right_term)
left_term = operator
operator = None
continue
elif expression[0] == "\\":
operator = ComplementOperator()
expression = expression[1:]
continue
elif expression[0] == "&":
operator = IntersectOperator()
expression = expression[1:]
continue
elif expression[0] == "|":
operator = UnionOperator()
expression = expression[1:]
continue
else:
if (left_term is None):
left_term, primitiveexpression = __resolve_primitive_expression(expression)
expression = expression[len(primitiveexpression):]
continue
else:
right_term, primitiveexpression = __resolve_primitive_expression(expression)
expression = expression[len(primitiveexpression):]
operator.set_left_term(left_term)
operator.set_right_term(right_term)
left_term = operator
operator = None
continue
def __resolve_primitive_expression(expression):
"""
Resolve a primitive expression and return a RSEAttribute object
:param expression: String of the expresssion
:returns: Tuple of RSEAttribute, primitive expression
"""
primitiveexpression = re.match(PRIMITIVE, expression).group()
if ('=' in primitiveexpression):
keyvalue = primitiveexpression.split("=")
return (RSEAttributeEqualCheck(keyvalue[0], keyvalue[1]), primitiveexpression)
elif ('<' in primitiveexpression):
keyvalue = primitiveexpression.split("<")
return (RSEAttributeSmallerCheck(keyvalue[0], keyvalue[1]), primitiveexpression)
elif ('>' in primitiveexpression):
keyvalue = primitiveexpression.split(">")
return (RSEAttributeLargerCheck(keyvalue[0], keyvalue[1]), primitiveexpression)
elif ('*' in primitiveexpression):
return (RSEAll(), primitiveexpression)
else:
return (RSEAttributeEqualCheck(key=primitiveexpression), primitiveexpression)
def __extract_term(expression):
"""
Extract a term from an expression with parantheses
:param expression: The expression starting with a '('
:return: The extracted term string
"""
open_parantheses = 0
i = 0
for char in expression:
if (char == '('):
open_parantheses += 1
elif (char == ')'):
open_parantheses -= 1
if (open_parantheses == 0):
return expression[1:i]
i = i + 1
raise SystemError('This point in the code should not be reachable')
class BaseExpressionElement(object, metaclass=abc.ABCMeta):
@abc.abstractmethod
def resolve_elements(self, session):
"""
Resolve the ExpressionElement and return a set of RSE ids
:param session: Database session in use
:returns: (Set of RSE ids, Dictionary of RSE dicts)
:rtype: (Set of Strings, Dictionary of RSE dicts organized by rse_id)
"""
pass
class RSEAll(BaseExpressionElement):
"""
Representation of all RSEs
"""
def resolve_elements(self, session):
"""
Inherited from :py:func:`BaseExpressionElement.resolve_elements`
"""
output = list_rses(session=session)
if not output:
return (set(), {})
rse_dict = {}
for rse in output:
rse_dict[rse['id']] = rse
return (set([rse['id'] for rse in output]), rse_dict)
class RSEAttributeEqualCheck(BaseExpressionElement):
"""
Representation of an RSE Attribute with Equal Check
"""
def __init__(self, key, value=True):
"""
Creates an RSEAttribute representation
:param key: Key of the RSE Attribute.
:param value: Value of the RSE Attribute.
"""
self.key = key
self.value = value
def resolve_elements(self, session):
"""
Inherited from :py:func:`BaseExpressionElement.resolve_elements`
"""
output = list_rses({self.key: self.value}, session=session)
if not output:
return (set(), {})
rse_dict = {}
for rse in output:
rse_dict[rse['id']] = rse
return (set([rse['id'] for rse in output]), rse_dict)
class RSEAttributeSmallerCheck(BaseExpressionElement):
"""
Representation of an RSE Attribute with Smaller (<) Check
"""
def __init__(self, key, value=True):
"""
Creates an RSEAttribute representation
:param key: Key of the RSE Attribute.
:param value: Value of the RSE Attribute.
"""
self.key = key
self.value = value
def resolve_elements(self, session):
"""
Inherited from :py:func:`BaseExpressionElement.resolve_elements`
"""
rse_list = get_rses_with_attribute(key=self.key, session=session)
if not rse_list:
return (set(), {})
output = []
rse_dict = {}
for rse in rse_list:
try:
if float(get_rse_attribute(rse['id'], self.key, session=session)) < float(self.value):
rse_dict[rse['id']] = rse
output.append(rse['id'])
except ValueError:
continue
return (set(output), rse_dict)
class RSEAttributeLargerCheck(BaseExpressionElement):
"""
Representation of an RSE Attribute with Larger (>) Check
"""
def __init__(self, key, value=True):
"""
Creates an RSEAttribute representation
:param key: Key of the RSE Attribute.
:param value: Value of the RSE Attribute.
"""
self.key = key
self.value = value
def resolve_elements(self, session):
"""
Inherited from :py:func:`BaseExpressionElement.resolve_elements`
"""
rse_list = get_rses_with_attribute(key=self.key, session=session)
if not rse_list:
return (set(), {})
output = []
rse_dict = {}
for rse in rse_list:
try:
if float(get_rse_attribute(rse['id'], self.key, session=session)) > float(self.value):
rse_dict[rse['id']] = rse
output.append(rse['id'])
except ValueError:
continue
return (set(output), rse_dict)
class BaseRSEOperator(BaseExpressionElement, metaclass=abc.ABCMeta):
@abc.abstractmethod
def set_left_term(self, left_term):
"""
Set the left site of the term
:param left_term: Left term
"""
pass
@abc.abstractmethod
def set_right_term(self, right_term):
"""
Set the right site of the term
:param left_term: Left term
"""
pass
class ComplementOperator(BaseRSEOperator):
"""
Representation of the complement operator
"""
def __init__(self):
"""
Create a ComplementOperator representation
"""
self.left_term = None
self.right_term = None
def set_left_term(self, left_term):
"""
Inherited from :py:func:`BaseRSEOperator.set_left_term`
"""
self.left_term = left_term
def set_right_term(self, right_term):
"""
Inherited from :py:func:`BaseRSEOperator.set_right_term`
"""
self.right_term = right_term
def resolve_elements(self, session):
"""
Inherited from :py:func:`BaseExpressionElement.resolve_elements`
"""
left_term_tuple = self.left_term.resolve_elements(session=session)
right_term_tuple = self.right_term.resolve_elements(session=session)
return (left_term_tuple[0] - right_term_tuple[0], dict(list(left_term_tuple[1].items()) + list(right_term_tuple[1].items())))
class UnionOperator(BaseRSEOperator):
"""
Representation of the or operator
"""
def __init__(self):
"""
Create a UnionOperator representation
"""
self.left_term = None
self.right_term = None
def set_left_term(self, left_term):
"""
Inherited from :py:func:`BaseRSEOperator.set_left_term`
"""
self.left_term = left_term
def set_right_term(self, right_term):
"""
Inherited from :py:func:`BaseRSEOperator.set_right_term`
"""
self.right_term = right_term
def resolve_elements(self, session):
"""
Inherited from :py:func:`BaseExpressionElement.resolve_elements`
"""
left_term_tuple = self.left_term.resolve_elements(session=session)
right_term_tuple = self.right_term.resolve_elements(session=session)
return (left_term_tuple[0] | right_term_tuple[0], dict(list(left_term_tuple[1].items()) + list(right_term_tuple[1].items())))
class IntersectOperator(BaseRSEOperator):
"""
Representation of the intersect operator
"""
def __init__(self):
"""
Create a IntersectOperator representation
"""
self.left_term = None
self.right_term = None
def set_left_term(self, left_term):
"""
Inherited from :py:func:`BaseRSEOperator.set_left_term`
"""
self.left_term = left_term
def set_right_term(self, right_term):
"""
Inherited from :py:func:`BaseRSEOperator.set_right_term`
"""
self.right_term = right_term
def resolve_elements(self, session):
"""
Inherited from :py:func:`BaseExpressionElement.resolve_elements`
"""
left_term_tuple = self.left_term.resolve_elements(session=session)
right_term_tuple = self.right_term.resolve_elements(session=session)
return (left_term_tuple[0] & right_term_tuple[0], dict(list(left_term_tuple[1].items()) + list(right_term_tuple[1].items())))