class SchevoStoreBackend(object):
DEFAULT_CACHE_SIZE = 100000
description = 'Built-in backend, based on Durus 3.4'
backend_args_help = """
Use "schevostore:///:memory:" for an in-memory database.
cache_size=%(DEFAULT_CACHE_SIZE)i (int)
Set the size of the in-memory object cache to SIZE, which is an
integer specifying the maximum number of objects to keep in the
cache.
fp=None (file-like object)
Optional file object to use instead of an actual file in the
filesystem.
""" % locals()
__test__ = False
BTree = BTree
PDict = PersistentDict
PList = PersistentList
TestMethods_CreatesDatabase = TestMethods_CreatesDatabase
TestMethods_CreatesSchema = TestMethods_CreatesSchema
TestMethods_EvolvesSchemata = TestMethods_EvolvesSchemata
def __init__(self,
database,
fp=None,
cache_size=DEFAULT_CACHE_SIZE,
):
self.database = database
if database == ':memory:' and fp is None:
fp = StringIO()
self.fp = fp
self.cache_size = cache_size
self.is_open = False
self.open()
@classmethod
def usable_by_backend(cls, filename):
"""Return (`True`, *additional backend args*) if the named
file is usable by this backend, or `False` if not."""
# Get first 128 bytes of file.
f = open(filename, 'rb')
try:
try:
header = f.read(128)
except IOError:
if sys.platform == 'win32':
raise DatabaseFileLocked()
else:
raise
finally:
f.close()
# Look for Durus file storage signature and schevo.store
# module signature.
if header[:5] == 'DFS20':
if 'schevo.store.persistent_dict' in header:
return (True, {})
return False
@property
def has_db(self):
"""Return `True` if the backend contains a Schevo database."""
return self.get_root().has_key('SCHEVO')
def close(self):
"""Close the underlying storage (and the connection if
needed)."""
self.storage.close()
self.is_open = False
def get_root(self):
"""Return the backend's `root` object."""
return self.conn.get_root()
def commit(self):
"""Commit the current transaction."""
self.conn.commit()
def open(self):
"""Open the underlying storage based on initial arguments."""
if not self.is_open:
try:
self.storage = FileStorage(self.database, fp=self.fp)
except RuntimeError:
raise DatabaseFileLocked()
self.conn = Connection(self.storage, cache_size=self.cache_size)
self.is_open = True
def pack(self):
"""Pack the underlying storage."""
self.conn.pack()
def rollback(self):
"""Abort the current transaction."""
self.conn.abort()
class SchevoStoreBackend(object):
description = 'Built-in backend, based on Durus 3.4'
backend_args_help = """
cache_size=SIZE
Set the size of the in-memory object cache to SIZE, which is an
integer specifying the maximum number of objects to keep in the
cache.
"""
__test__ = False
BTree = BTree
PDict = PersistentDict
PList = PersistentList
TestMethods_CreatesDatabase = TestMethods_CreatesDatabase
TestMethods_CreatesSchema = TestMethods_CreatesSchema
TestMethods_EvolvesSchemata = TestMethods_EvolvesSchemata
def __init__(self, filename, fp=None, cache_size=100000):
"""Create a new `SchevoStoreBackend` instance.
- `filename`: Name of file to open with this backend. If
`None`, the backend will expect that you passed in a value
for `fp` instead.
- `fp`: (optional) File-like object to use instead of an
actual file in the filesystem.
- `cache_size`: Maximum number of objects to keep in the
in-memory object cache.
"""
self._filename = filename
self._fp = fp
self._cache_size = cache_size
self._is_open = False
self.open()
@classmethod
def args_from_string(cls, s):
"""Return a dictionary of keyword arguments based on a string given
to a command-line tool."""
kw = {}
if s is not None:
for arg in (p.strip() for p in s.split(',')):
name, value = (p2.strip() for p2 in arg.split('='))
if name == 'cache_size':
kw[name] = int(value)
else:
raise KeyError(
'%s is not a valid name for backend args' % name)
return kw
@classmethod
def usable_by_backend(cls, filename):
"""Return (`True`, *additional backend args*) if the named
file is usable by this backend, or `False` if not."""
# Get first 128 bytes of file.
f = open(filename, 'rb')
try:
try:
header = f.read(128)
except IOError:
if sys.platform == 'win32':
raise DatabaseFileLocked()
else:
raise
finally:
f.close()
# Look for Durus file storage signature and schevo.store
# module signature.
if header[:5] == 'DFS20':
if 'schevo.store.persistent_dict' in header:
return (True, {})
return False
@property
def has_db(self):
"""Return `True` if the backend contains a Schevo database."""
return self.get_root().has_key('SCHEVO')
def close(self):
"""Close the underlying storage (and the connection if
needed)."""
self.storage.close()
self._is_open = False
def get_root(self):
"""Return the backend's `root` object."""
return self.conn.get_root()
def commit(self):
"""Commit the current transaction."""
self.conn.commit()
def open(self):
"""Open the underlying storage based on initial arguments."""
if not self._is_open:
try:
self.storage = FileStorage(self._filename, fp=self._fp)
except RuntimeError:
raise DatabaseFileLocked()
self.conn = Connection(self.storage, cache_size=self._cache_size)
self._is_open = True
def pack(self):
"""Pack the underlying storage."""
self.conn.pack()
def rollback(self):
"""Abort the current transaction."""
self.conn.abort()