115 lines
3.2 KiB
Python
115 lines
3.2 KiB
Python
# scopes.storage.common
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"""Common utility stuff for the scopes.storage package."""
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import base64
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from sqlalchemy import create_engine, MetaData, text
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from sqlalchemy import Integer
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from sqlalchemy.dialects.sqlite import JSON
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import threading
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# predefined db-specific definitions, usable for SQLite;
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# may be overriden by import of ``scopes.storage.db.<dbname>``
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def sessionFactory(engine):
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return engine.connect
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def getEngine(dbtype, dbname, user, pw, host='localhost', port=5432, **kw):
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return create_engine('%s:///%s' % (dbtype, dbname), **kw)
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def mark_changed(session):
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pass
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def commit(conn):
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conn.commit()
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IdType = Integer
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JsonType = JSON
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class StorageFactory(object):
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engine = Session = None
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sessionFactory = sessionFactory
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getEngine = getEngine
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mark_changed = mark_changed
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commit = commit
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IdType = IdType
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JsonType = JsonType
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def __call__(self, schema=None):
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st = Storage(schema=schema)
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st.setup(self)
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return st
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def setup(self, config):
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self.engine = self.getEngine(config.dbengine, config.dbname,
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config.dbuser, config.dbpassword)
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self.Session = self.sessionFactory
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# you may put something like this in your code:
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#scopes.storage.common.factory = StorageFactory(config)
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# and then call at appropriate places:
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#storage = scopes.storage.common.factory(schema=...)
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class Storage(object):
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def __init__(self, schema=None):
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self.engine = engine
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self.session = Session()
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self.schema = schema
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self.metadata = MetaData(schema=schema)
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self.containers = {}
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def create(self, cls):
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container = cls(self)
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self.add(container)
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return container
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def add(self, container):
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self.containers[container.itemFactory.prefix] = container
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def getItem(self, uid):
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prefix, id = uid.split('-')
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id = int(id)
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container = self.containers.get(prefix)
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if container is None:
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container = self.create(registry[prefix])
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return container.get(id)
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def getExistingTable(self, tableName):
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metadata = self.metadata
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schema = self.schema
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metadata.reflect(self.engine)
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return metadata.tables.get((schema and schema + '.' or '') + tableName)
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def dropTable(self, tableName):
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with self.engine.begin() as conn:
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prefix = self.schema and self.schema + '.' or ''
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conn.execute(text('drop table if exists %s%s' % (prefix, tableName)))
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def resetSequence(self, tableName, colName, v):
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sq = ('alter sequence %s.%s_%s_seq restart %i' %
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(self.schema, tableName, colName, v))
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with self.engine.begin() as conn:
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conn.execute(text(sq))
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# store information about container implementations, identified by a uid prefix.
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registry = {}
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def registerContainerClass(cls):
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prefix = cls.itemFactory.prefix
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if prefix in registry:
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raise ValueError("prefix '%s' already registered!" % prefix)
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registry[prefix] = cls
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cls.headCols = cols = tuple(f.lower() for f in cls.itemFactory.headFields)
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if cls.indexes is None:
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cls.indexes = [cols[i:] for i in range(len(cols))]
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return cls
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