def _collect_elements(self):
# If expr is a ValueExpr, we must seek out the TableExprs that it
# references, build their ASTs, and mark them in our QueryContext
# For now, we need to make the simplifying assumption that a value
# expression that is being translated only depends on a single table
# expression.
source_expr = self.query_expr
# hm, is this the best place for this?
root_op = source_expr.op()
if isinstance(root_op, ops.Join) and not isinstance(
root_op, ops.MaterializedJoin):
# Unmaterialized join
source_expr = source_expr.materialize()
if isinstance(root_op, ops.TableNode):
self._collect(source_expr, toplevel=True)
if self.table_set is None:
raise com.InternalError('no table set')
else:
# Expressions not depending on any table
if isinstance(root_op, ops.ExpressionList):
self.select_set = source_expr.exprs()
else:
self.select_set = [source_expr]
def _get_cursor(self):
try:
cursor = self.connection_pool.popleft()
except IndexError: # deque is empty
with self.lock:
# NB: Do not put a lock around the entire if statement.
# This will cause a deadlock because _new_cursor calls the
# ImpalaCursor constructor which takes a lock to increment the
# connection pool size.
connection_pool_size = self.connection_pool_size
if connection_pool_size < self.max_pool_size:
return self._new_cursor()
raise com.InternalError('Too many concurrent / hung queries')
else:
if (cursor.database != self.database
or cursor.options != self.options):
return self._new_cursor()
cursor.released = False
return cursor
