130 lines
3.8 KiB
Python
130 lines
3.8 KiB
Python
# Copyright 2015 DataStax, Inc.
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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 __future__ import division
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from datetime import datetime
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from cassandra.cqlengine import UnicodeMixin, ValidationError
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import sys
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if sys.version_info >= (2, 7):
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def get_total_seconds(td):
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return td.total_seconds()
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else:
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def get_total_seconds(td):
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# integer division used here to emulate built-in total_seconds
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return ((86400 * td.days + td.seconds) * 10 ** 6 + td.microseconds) / 10 ** 6
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class QueryValue(UnicodeMixin):
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"""
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Base class for query filter values. Subclasses of these classes can
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be passed into .filter() keyword args
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"""
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format_string = '%({0})s'
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def __init__(self, value):
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self.value = value
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self.context_id = None
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def __unicode__(self):
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return self.format_string.format(self.context_id)
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def set_context_id(self, ctx_id):
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self.context_id = ctx_id
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def get_context_size(self):
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return 1
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def update_context(self, ctx):
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ctx[str(self.context_id)] = self.value
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class BaseQueryFunction(QueryValue):
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"""
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Base class for filtering functions. Subclasses of these classes can
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be passed into .filter() and will be translated into CQL functions in
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the resulting query
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"""
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pass
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class TimeUUIDQueryFunction(BaseQueryFunction):
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def __init__(self, value):
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"""
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:param value: the time to create bounding time uuid from
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:type value: datetime
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"""
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if not isinstance(value, datetime):
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raise ValidationError('datetime instance is required')
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super(TimeUUIDQueryFunction, self).__init__(value)
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def to_database(self, val):
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epoch = datetime(1970, 1, 1, tzinfo=val.tzinfo)
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offset = get_total_seconds(epoch.tzinfo.utcoffset(epoch)) if epoch.tzinfo else 0
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return int((get_total_seconds(val - epoch) - offset) * 1000)
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def update_context(self, ctx):
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ctx[str(self.context_id)] = self.to_database(self.value)
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class MinTimeUUID(TimeUUIDQueryFunction):
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"""
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return a fake timeuuid corresponding to the smallest possible timeuuid for the given timestamp
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http://cassandra.apache.org/doc/cql3/CQL.html#timeuuidFun
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"""
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format_string = 'MinTimeUUID(%({0})s)'
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class MaxTimeUUID(TimeUUIDQueryFunction):
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"""
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return a fake timeuuid corresponding to the largest possible timeuuid for the given timestamp
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http://cassandra.apache.org/doc/cql3/CQL.html#timeuuidFun
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"""
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format_string = 'MaxTimeUUID(%({0})s)'
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class Token(BaseQueryFunction):
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"""
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compute the token for a given partition key
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http://cassandra.apache.org/doc/cql3/CQL.html#tokenFun
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"""
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def __init__(self, *values):
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if len(values) == 1 and isinstance(values[0], (list, tuple)):
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values = values[0]
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super(Token, self).__init__(values)
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self._columns = None
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def set_columns(self, columns):
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self._columns = columns
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def get_context_size(self):
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return len(self.value)
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def __unicode__(self):
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token_args = ', '.join('%({0})s'.format(self.context_id + i) for i in range(self.get_context_size()))
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return "token({0})".format(token_args)
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def update_context(self, ctx):
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for i, (col, val) in enumerate(zip(self._columns, self.value)):
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ctx[str(self.context_id + i)] = col.to_database(val)
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