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import logging
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from threading import RLock
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from sqlalchemy import create_engine
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from migrate.versioning.util import construct_engine
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from sqlalchemy.pool import NullPool
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from sqlalchemy.schema import MetaData, Column, Index
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from sqlalchemy.schema import Table as SQLATable
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from sqlalchemy import Integer
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from dataset.persistence.table import Table
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log = logging.getLogger(__name__)
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class Database(object):
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def __init__(self, url):
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kw = {}
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if url.startswith('postgres'):
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kw['poolclass'] = NullPool
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engine = create_engine(url, **kw)
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self.lock = RLock()
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self.url = url
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self.engine = construct_engine(engine)
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self.metadata = MetaData()
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self.metadata.bind = self.engine
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self.tables = {}
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self.indexes = {}
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def create_table(table_name):
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with self.lock:
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log.debug("Creating table: %s on %r" % (table_name, self.engine))
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table = SQLATable(table_name, self.metadata)
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col = Column('id', Integer, primary_key=True)
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table.append_column(col)
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table.create(self.engine)
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self.tables[table_name] = table
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return Table(self, table)
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def load_table(self, table_name):
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with self.lock:
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log.debug("Loading table: %s on %r" % (table_name, self))
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table = SQLATable(table_name, self.metadata, autoload=True)
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self.tables[table_name] = table
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return Table(self, table)
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def get_table(self, table_name):
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with self.lock:
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if table_name in self.tables:
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return Table(self, self.tables[table_name])
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if self.engine.has_table(table_name):
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return load_table(engine, table_name)
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else:
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return create_table(engine, table_name)
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def __getitem__(self, table_name):
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return self.get_table(table_name)
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@classmethod
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def connect(self, url):
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return Database(url)
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def __repr__(self):
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return '<Database(%s)>' % self.url
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