+def _find_sqlite_db_dirs_posix():
+ db_dirs = []
+ if 'XDG_CACHE_HOME' in os.environ:
+ db_dirs.append(os.environ['XDG_CACHE_HOME'])
+ home_cache = os.path.expanduser('~/.cache')
+ if home_cache not in db_dirs:
+ db_dirs.append(home_cache)
+ return db_dirs
+
+
+def find_sqlite_db_dirs():
+ if os.name == 'posix':
+ return _find_sqlite_db_dirs_posix()
+ raise OSError("Unknow OS")
+
+
+def find_sqlite_dburi(db_dirs=None):
+ if db_dirs is None:
+ db_dirs = find_sqlite_db_dirs()
+ for d in db_dirs:
+ db_file = os.path.join(d, 'm_librarian.sqlite')
+ if os.path.exists(db_file):
+ break
+ else:
+ # octal; -rw-------;
+ # make the database file/directory readable/writeable only by the user
+ os.umask(0o66)
+ db_dir = db_dirs[0]
+ try:
+ os.makedirs(db_dir)
+ except OSError: # Perhaps already exists
+ pass
+ db_file = os.path.join(db_dir, 'm_librarian.sqlite')
+
+ return 'sqlite://%s' % db_file.replace(os.sep, '/')
+
+
+def open_db(db_uri=None):
+ if db_uri is None:
+ try:
+ db_uri = get_config().get('database', 'URI')
+ except Exception:
+ db_uri = find_sqlite_dburi()
+
+ if '://' not in db_uri:
+ db_uri = 'sqlite://' + os.path.abspath(db_uri).replace(os.sep, '/')
+
+ sqlhub.processConnection = connection = connectionForURI(db_uri)
+
+ if connection.dbName == 'sqlite':
+ def lower(s):
+ if isinstance(s, string_type):
+ return s.lower()
+ return s
+
+ sqlite = connection.module
+
+ class MLConnection(sqlite.Connection):
+ def __init__(self, *args, **kwargs):
+ super(MLConnection, self).__init__(*args, **kwargs)
+ self.create_function('lower', 1, lower)
+
+ # This hack must be done at the very beginning, before the first query
+ connection._connOptions['factory'] = MLConnection
+
+ # Speedup SQLite connection
+ connection.query("PRAGMA synchronous=OFF")
+ connection.query("PRAGMA count_changes=OFF")
+ connection.query("PRAGMA journal_mode=MEMORY")
+ connection.query("PRAGMA temp_store=MEMORY")
+
+