在Airflow中，可以使用ShortCircuitOperator和BranchPythonOperator来实现在SLA未达成的情况下停止当前DAG的执行。下面是一个示例代码：

from datetime import datetime, timedelta
from airflow import DAG
from airflow.operators.dummy_operator import DummyOperator
from airflow.operators.python_operator import ShortCircuitOperator, BranchPythonOperator

default_args = {
    'owner': 'airflow',
    'start_date': datetime(2022, 1, 1),
    'retries': 0,
}

def check_sla(execution_date, sla):
    # 根据特定逻辑检查SLA是否达成，返回True或False
    # 可以根据自己的需求修改此函数
    return False

def stop_dag(execution_date, **kwargs):
    # 在SLA未达成的情况下停止DAG的执行
    dag_run = kwargs['dag_run']
    dag_run.set_state('failed')

dag = DAG('my_dag', schedule_interval='@daily', default_args=default_args)

start = DummyOperator(task_id='start', dag=dag)

check_sla_task = ShortCircuitOperator(
    task_id='check_sla',
    python_callable=check_sla,
    op_kwargs={'sla': timedelta(hours=1)},  # 设置SLA时间
    provide_context=True,
    dag=dag,
)

stop_dag_task = BranchPythonOperator(
    task_id='stop_dag',
    python_callable=stop_dag,
    provide_context=True,
    dag=dag,
)

end = DummyOperator(task_id='end', dag=dag)

start >> check_sla_task >> stop_dag_task >> end