from beaker._compat import pickle import logging import pickle from datetime import datetime from beaker.container import OpenResourceNamespaceManager, Container from beaker.exceptions import InvalidCacheBackendError, MissingCacheParameter from beaker.synchronization import file_synchronizer, null_synchronizer from beaker.util import verify_directory, SyncDict log = logging.getLogger(__name__) sa = None class SqlaNamespaceManager(OpenResourceNamespaceManager): binds = SyncDict() tables = SyncDict() @classmethod def _init_dependencies(cls): global sa if sa is not None: return try: import sqlalchemy as sa except ImportError: raise InvalidCacheBackendError("SQLAlchemy, which is required by " "this backend, is not installed") def __init__(self, namespace, bind, table, data_dir=None, lock_dir=None, **kwargs): """Create a namespace manager for use with a database table via SQLAlchemy. ``bind`` SQLAlchemy ``Engine`` or ``Connection`` object ``table`` SQLAlchemy ``Table`` object in which to store namespace data. This should usually be something created by ``make_cache_table``. """ OpenResourceNamespaceManager.__init__(self, namespace) if lock_dir: self.lock_dir = lock_dir elif data_dir: self.lock_dir = data_dir + "/container_db_lock" if self.lock_dir: verify_directory(self.lock_dir) self.bind = self.__class__.binds.get(str(bind.url), lambda: bind) self.table = self.__class__.tables.get('%s:%s' % (bind.url, table.name), lambda: table) self.hash = {} self._is_new = False self.loaded = False def get_access_lock(self): return null_synchronizer() def get_creation_lock(self, key): return file_synchronizer( identifier="databasecontainer/funclock/%s" % self.namespace, lock_dir=self.lock_dir) def do_open(self, flags, replace): if self.loaded: self.flags = flags return select = sa.select([self.table.c.data], (self.table.c.namespace == self.namespace)) result = self.bind.execute(select).fetchone() if not result: self._is_new = True self.hash = {} else: self._is_new = False try: self.hash = result['data'] except (IOError, OSError, EOFError, pickle.PickleError, pickle.PickleError): log.debug("Couln't load pickle data, creating new storage") self.hash = {} self._is_new = True self.flags = flags self.loaded = True def do_close(self): if self.flags is not None and (self.flags == 'c' or self.flags == 'w'): if self._is_new: insert = self.table.insert() self.bind.execute(insert, namespace=self.namespace, data=self.hash, accessed=datetime.now(), created=datetime.now()) self._is_new = False else: update = self.table.update(self.table.c.namespace == self.namespace) self.bind.execute(update, data=self.hash, accessed=datetime.now()) self.flags = None def do_remove(self): delete = self.table.delete(self.table.c.namespace == self.namespace) self.bind.execute(delete) self.hash = {} self._is_new = True def __getitem__(self, key): return self.hash[key] def __contains__(self, key): return key in self.hash def __setitem__(self, key, value): self.hash[key] = value def __delitem__(self, key): del self.hash[key] def keys(self): return self.hash.keys() class SqlaContainer(Container): namespace_manager = SqlaNamespaceManager def make_cache_table(metadata, table_name='beaker_cache', schema_name=None): """Return a ``Table`` object suitable for storing cached values for the namespace manager. Do not create the table.""" return sa.Table(table_name, metadata, sa.Column('namespace', sa.String(255), primary_key=True), sa.Column('accessed', sa.DateTime, nullable=False), sa.Column('created', sa.DateTime, nullable=False), sa.Column('data', sa.PickleType, nullable=False), schema=schema_name if schema_name else metadata.schema)