def _ping_listener(engine, dbapi_conn, connection_rec, connection_proxy):
"""Ensures that MySQL, PostgreSQL or DB2 connections are alive.
Borrowed from:
http://groups.google.com/group/sqlalchemy/msg/a4ce563d802c929f
"""
cursor = dbapi_conn.cursor()
try:
ping_sql = 'select 1'
if engine.name == 'ibm_db_sa':
# DB2 requires a table expression
ping_sql = 'select 1 from (values (1)) AS t1'
cursor.execute(ping_sql)
except Exception as ex:
if engine.dialect.is_disconnect(ex, dbapi_conn, cursor):
msg = _LW('Database server has gone away: %s') % ex
LOG.warning(msg)
# if the database server has gone away, all connections in the pool
# have become invalid and we can safely close all of them here,
# rather than waste time on checking of every single connection
engine.dispose()
# this will be handled by SQLAlchemy and will force it to create
# a new connection and retry the original action
raise sqla_exc.DisconnectionError(msg)
else:
raise
def _mysql_check_effective_sql_mode(engine):
"""Logs a message based on the effective SQL mode for MySQL connections."""
realmode = _mysql_get_effective_sql_mode(engine)
if realmode is None:
LOG.warning(_LW('Unable to detect effective SQL mode'))
return
LOG.debug('MySQL server mode set to %s', realmode)
# 'TRADITIONAL' mode enables several other modes, so
# we need a substring match here
if not ('TRADITIONAL' in realmode.upper() or
'STRICT_ALL_TABLES' in realmode.upper()):
LOG.warning(_LW("MySQL SQL mode is '%s', "
"consider enabling TRADITIONAL or STRICT_ALL_TABLES"),
realmode)
def _wait_child(self):
try:
# Don't block if no child processes have exited
pid, status = os.waitpid(0, os.WNOHANG)
if not pid:
return None
except OSError as exc:
if exc.errno not in (errno.EINTR, errno.ECHILD):
raise
return None
if os.WIFSIGNALED(status):
sig = os.WTERMSIG(status)
LOG.info(_LI("Child %(pid)d killed by signal %(sig)d"), dict(pid=pid, sig=sig))
else:
code = os.WEXITSTATUS(status)
LOG.info(_LI("Child %(pid)s exited with status %(code)d"), dict(pid=pid, code=code))
if pid not in self.children:
LOG.warning(_LW("pid %d not in child list"), pid)
return None
wrap = self.children.pop(pid)
wrap.children.remove(pid)
return wrap
def _wait_child(self):
try:
# Don't block if no child processes have exited
pid, status = os.waitpid(0, os.WNOHANG)
if not pid:
return None
except OSError as exc:
if exc.errno not in (errno.EINTR, errno.ECHILD):
raise
return None
if os.WIFSIGNALED(status):
sig = os.WTERMSIG(status)
LOG.info(_LI('Child %(pid)d killed by signal %(sig)d'),
dict(pid=pid, sig=sig))
else:
code = os.WEXITSTATUS(status)
LOG.info(_LI('Child %(pid)s exited with status %(code)d'),
dict(pid=pid, code=code))
if pid not in self.children:
LOG.warning(_LW('pid %d not in child list'), pid)
return None
wrap = self.children.pop(pid)
wrap.children.remove(pid)
return wrap
def _inner():
if initial_delay:
greenthread.sleep(initial_delay)
try:
while self._running:
start = timeutils.utcnow()
self.f(*self.args, **self.kw)
end = timeutils.utcnow()
if not self._running:
break
delay = interval - timeutils.delta_seconds(start, end)
if delay <= 0:
LOG.warn(
_LW('task run outlasted interval by %s sec') %
-delay)
greenthread.sleep(delay if delay > 0 else 0)
except LoopingCallDone as e:
self.stop()
done.send(e.retvalue)
except Exception:
LOG.exception(_LE('in fixed duration looping call'))
done.send_exception(*sys.exc_info())
return
else:
done.send(True)
def _inner():
if initial_delay:
greenthread.sleep(initial_delay)
try:
while self._running:
start = timeutils.utcnow()
self.f(*self.args, **self.kw)
end = timeutils.utcnow()
if not self._running:
break
delay = interval - timeutils.delta_seconds(start, end)
if delay <= 0:
LOG.warn(_LW('task run outlasted interval by %s sec') %
-delay)
greenthread.sleep(delay if delay > 0 else 0)
except LoopingCallDone as e:
self.stop()
done.send(e.retvalue)
except Exception:
LOG.exception(_LE('in fixed duration looping call'))
done.send_exception(*sys.exc_info())
return
else:
done.send(True)
def create_engine(sql_connection, sqlite_fk=False, mysql_sql_mode=None,
idle_timeout=3600,
connection_debug=0, max_pool_size=None, max_overflow=None,
pool_timeout=None, sqlite_synchronous=True,
connection_trace=False, max_retries=10, retry_interval=10):
"""Return a new SQLAlchemy engine."""
connection_dict = sqlalchemy.engine.url.make_url(sql_connection)
engine_args = {
"pool_recycle": idle_timeout,
'convert_unicode': True,
}
logger = logging.getLogger('sqlalchemy.engine')
# Map SQL debug level to Python log level
if connection_debug >= 100:
logger.setLevel(logging.DEBUG)
elif connection_debug >= 50:
logger.setLevel(logging.INFO)
else:
logger.setLevel(logging.WARNING)
if "sqlite" in connection_dict.drivername:
if sqlite_fk:
engine_args["listeners"] = [SqliteForeignKeysListener()]
engine_args["poolclass"] = NullPool
if sql_connection == "sqlite://":
engine_args["poolclass"] = StaticPool
engine_args["connect_args"] = {'check_same_thread': False}
else:
if max_pool_size is not None:
engine_args['pool_size'] = max_pool_size
if max_overflow is not None:
engine_args['max_overflow'] = max_overflow
if pool_timeout is not None:
engine_args['pool_timeout'] = pool_timeout
engine = sqlalchemy.create_engine(sql_connection, **engine_args)
sqlalchemy.event.listen(engine, 'checkin', _thread_yield)
if engine.name in ('ibm_db_sa', 'mysql', 'postgresql'):
ping_callback = functools.partial(_ping_listener, engine)
sqlalchemy.event.listen(engine, 'checkout', ping_callback)
if engine.name == 'mysql':
if mysql_sql_mode:
_mysql_set_mode_callback(engine, mysql_sql_mode)
elif 'sqlite' in connection_dict.drivername:
if not sqlite_synchronous:
sqlalchemy.event.listen(engine, 'connect',
_synchronous_switch_listener)
sqlalchemy.event.listen(engine, 'connect', _add_regexp_listener)
if connection_trace and engine.dialect.dbapi.__name__ == 'MySQLdb':
_patch_mysqldb_with_stacktrace_comments()
try:
engine.connect()
except sqla_exc.OperationalError as e:
if not _is_db_connection_error(e.args[0]):
raise
remaining = max_retries
if remaining == -1:
remaining = 'infinite'
while True:
msg = _LW('SQL connection failed. %s attempts left.')
LOG.warning(msg % remaining)
if remaining != 'infinite':
remaining -= 1
time.sleep(retry_interval)
try:
engine.connect()
break
except sqla_exc.OperationalError as e:
if (remaining != 'infinite' and remaining == 0) or \
not _is_db_connection_error(e.args[0]):
raise
return engine
def paginate_query(query, model, limit, sort_keys, marker=None,
sort_dir=None, sort_dirs=None):
"""Returns a query with sorting / pagination criteria added.
Pagination works by requiring a unique sort_key, specified by sort_keys.
(If sort_keys is not unique, then we risk looping through values.)
We use the last row in the previous page as the 'marker' for pagination.
So we must return values that follow the passed marker in the order.
With a single-valued sort_key, this would be easy: sort_key > X.
With a compound-values sort_key, (k1, k2, k3) we must do this to repeat
the lexicographical ordering:
(k1 > X1) or (k1 == X1 && k2 > X2) or (k1 == X1 && k2 == X2 && k3 > X3)
We also have to cope with different sort_directions.
Typically, the id of the last row is used as the client-facing pagination
marker, then the actual marker object must be fetched from the db and
passed in to us as marker.
:param query: the query object to which we should add paging/sorting
:param model: the ORM model class
:param limit: maximum number of items to return
:param sort_keys: array of attributes by which results should be sorted
:param marker: the last item of the previous page; we returns the next
results after this value.
:param sort_dir: direction in which results should be sorted (asc, desc)
:param sort_dirs: per-column array of sort_dirs, corresponding to sort_keys
:rtype: sqlalchemy.orm.query.Query
:return: The query with sorting/pagination added.
"""
if 'id' not in sort_keys:
# TODO(justinsb): If this ever gives a false-positive, check
# the actual primary key, rather than assuming its id
LOG.warning(_LW('Id not in sort_keys; is sort_keys unique?'))
assert(not (sort_dir and sort_dirs))
# Default the sort direction to ascending
if sort_dirs is None and sort_dir is None:
sort_dir = 'asc'
# Ensure a per-column sort direction
if sort_dirs is None:
sort_dirs = [sort_dir for _sort_key in sort_keys]
assert(len(sort_dirs) == len(sort_keys))
# Add sorting
for current_sort_key, current_sort_dir in zip(sort_keys, sort_dirs):
try:
sort_dir_func = {
'asc': sqlalchemy.asc,
'desc': sqlalchemy.desc,
}[current_sort_dir]
except KeyError:
raise ValueError(_("Unknown sort direction, "
"must be 'desc' or 'asc'"))
try:
sort_key_attr = getattr(model, current_sort_key)
except AttributeError:
raise InvalidSortKey()
query = query.order_by(sort_dir_func(sort_key_attr))
# Add pagination
if marker is not None:
marker_values = []
for sort_key in sort_keys:
v = getattr(marker, sort_key)
marker_values.append(v)
# Build up an array of sort criteria as in the docstring
criteria_list = []
for i in range(len(sort_keys)):
crit_attrs = []
for j in range(i):
model_attr = getattr(model, sort_keys[j])
crit_attrs.append((model_attr == marker_values[j]))
model_attr = getattr(model, sort_keys[i])
if sort_dirs[i] == 'desc':
crit_attrs.append((model_attr < marker_values[i]))
else:
crit_attrs.append((model_attr > marker_values[i]))
criteria = sqlalchemy.sql.and_(*crit_attrs)
criteria_list.append(criteria)
f = sqlalchemy.sql.or_(*criteria_list)
query = query.filter(f)
if limit is not None:
query = query.limit(limit)
return query