def Table(self, name, create=True, restricted=False, columns=None, keys=None,
timeout=None):
"""Returns the Table object for existing table name.
Args:
name: The table name.
create: If True creates the table if it does not exist.
restricted: Return a restricted table object.
columns: The number of columns in each row.
keys: The number of columns, left to right, that are primary keys. 0 for
all columns.
timeout: The number of seconds after last modification when the table
becomes invalid. 0 for no timeout. If None then the default cache
timeout is assumed.
Raises:
CacheTableNameInvalid: name is not a valid table name.
CacheTableNotFound: If the table does not exist.
Returns:
A Table object for name.
"""
if name in self._restricted:
raise exceptions.CacheTableRestricted(
'[{}] cache table [{}] is restricted.'.format(self.name, name))
table = self._tables.get(name, None)
if table:
if not table.deleted:
if columns is not None and columns != table.columns:
raise exceptions.CacheTableColumnsInvalid(
'[{}] cache table [{}] columns [{}] does not match existing {}.'
.format(self.name, name, columns, table.columns))
if keys is not None and keys != table.keys:
raise exceptions.CacheTableKeysInvalid(
'[{}] cache table [{}] keys [{}] does not match existing {}.'
.format(self.name, name, keys, table.keys))
return table
if not create:
raise exceptions.CacheTableNotFound(
'[{}] cache table [{}] not found.'.format(self.name, name))
if self._metadata:
rows = self._metadata.Select(Metadata.Row(name=name))
row = rows[0] if rows else None
if row:
metadata = Metadata(row)
return self._table_class(self,
name=metadata.name,
columns=metadata.columns,
keys=metadata.keys,
timeout=metadata.timeout,
modified=metadata.modified,
restricted=metadata.restricted)
if not create:
raise exceptions.CacheTableNotFound(
'[{}] cache table [{}] not found.'.format(self.name, name))
return self._CreateTable(name, restricted, columns, keys, timeout)
def _CreateTable(self, name, restricted, columns, keys, timeout):
"""Creates and returns a table object for name.
NOTE: This code is conditioned on self._metadata. If self._metadata is None
then we are initializing/updating the metadata table. The table name is
relaxed, in particular '_' is allowed in the table name. This avoids user
table name conflicts. Finally, self._metadata is set and the metadata
table row is updated to reflect any changes in the default timeout.
Args:
name: The table name.
restricted: Return a restricted table object.
columns: The number of columns in each row.
keys: The number of columns, left to right, that are primary keys. 0 for
all columns.
timeout: The number of seconds after last modification when the table
becomes invalid. 0 for no timeout.
Raises:
CacheTableNameInvalid: If name is invalid.
Returns:
A table object for name.
"""
if columns is None:
columns = 1
if columns < 1:
raise exceptions.CacheTableColumnsInvalid(
'[{}] table [{}] column count [{}] must be >= 1.'.format(
self.name, name, columns))
if keys is None:
keys = columns
if keys < 1 or keys > columns:
raise exceptions.CacheTableKeysInvalid(
'[{}] table [{}] primary key count [{}] must be >= 1 and <= {}.'
.format(self.name, name, keys, columns))
if timeout is None:
timeout = self.timeout
self._ImplementationCreateTable(name, columns, keys)
table = self._table_class(self,
name=name,
columns=columns,
keys=keys,
timeout=timeout,
modified=0,
restricted=restricted)
if self._metadata:
version = None
else:
# Initializing the metadata table -- get its Table object.
self._metadata = table
table.Validate()
rows = table.Select(Metadata.Row(name=name))
row = rows[0] if rows else None
if row:
metadata = Metadata(row)
if self.version is None:
self.version = metadata.version or ''
elif self.version != metadata.version:
raise exceptions.CacheVersionMismatch(
'[{}] cache version [{}] does not match [{}].'.format(
self.name, metadata.version, self.version),
metadata.version, self.version)
if self.timeout is None:
self.timeout = metadata.timeout
table.modified = 0
version = self.version
self._metadata.AddRows([Metadata.Row(
name=table.name,
columns=table.columns,
keys=table.keys,
timeout=table.timeout,
modified=table.modified,
restricted=table.restricted,
version=version)])
return table