sqlalchemy.py 文件源码

def _retry_on_exceptions(exc):
    if not isinstance(exc, exception.DBError):
        return False
    inn_e = exc.inner_exception
    if not isinstance(inn_e, sqlalchemy.exc.InternalError):
        return False
    return ((
        pymysql and
        isinstance(inn_e.orig, pymysql.err.InternalError) and
        (inn_e.orig.args[0] == pymysql.constants.ER.TABLE_DEF_CHANGED)
    ) or (
        # HACK(jd) Sometimes, PostgreSQL raises an error such as "current
        # transaction is aborted, commands ignored until end of transaction
        # block" on its own catalog, so we need to retry, but this is not
        # caught by oslo.db as a deadlock. This is likely because when we use
        # Base.metadata.create_all(), sqlalchemy itself gets an error it does
        # not catch or something. So this is why this function exists. To
        # paperover I guess.
        psycopg2
        and isinstance(inn_e.orig, psycopg2.InternalError)
        # current transaction is aborted
        and inn_e.orig.pgcode == '25P02'
    ))