# atomic() 方法 # from django.db import transaction#################### atomic()###################def atomic(using=None, savepoint=True): # 裝飾器和上下文管理器必須.()調(diào)用方法，因?yàn)檎嬲奶幚硎窃摲椒ǚ祷氐膶?shí)例，不是該方法本身 if callable(using):  return Atomic(DEFAULT_DB_ALIAS, savepoint)(using) # Decorator: @atomic(...) or context manager: with atomic(...): ... else:  return Atomic(using, savepoint)########################################### Atomic類 省略了非核心內(nèi)容############################################class Atomic(ContextDecorator): def __init__(self, using, savepoint): self.using = using self.savepoint = savepoint def __enter__(self): connection = get_connection(self.using) sid = connection.savepoint()   # 進(jìn)入with創(chuàng)建一個(gè)保存點(diǎn) # .............do def __exit__(self, exc_type, exc_value, traceback): if connection.in_atomic_block: # do............. if sid is not None:  try:   connection.savepoint_commit(sid)  # 提交事務(wù)  except DatabaseError:   try:    connection.savepoint_rollback(sid) # 捕獲數(shù)據(jù)庫(kù)異常回滾    connection.savepoint_commit(sid)   except Error:    connection.needs_rollback = True   raise ## 還有一段代碼是exec_type收到其他程序異常時(shí)候 全局回滾，此處省略 # do.................################################ ContextDecorator#################################class ContextDecorator(object): def __call__(self, func):  def inner(*args, **kwargs):   with self:    # 把函數(shù)放進(jìn)self的with上下文管理器，效果with相同，只是控制細(xì)粒度不同    return func(*args, **kwargs)  return inner

class Tran(): def __init__(self, conn=None, close=True):  if conn is None:     # 創(chuàng)建數(shù)據(jù)庫(kù)鏈接   print 'init'   self.conn = conn_tbkt()   self.cur = self.conn.cursor()   self.sql = [] def __enter__(self):       # 上下文管理器返回 sql語(yǔ)句列表 with Tran('tbkt_pxb') as sqls:  print 'enter'  return self.sql  # sql.append('select 1') def __exit__(self, exc_type, exc_val, exc_tb):  print 'exit'  try:   print self.sql        # 執(zhí)行sql   for s in self.sql:    self.cur.execute(s)   self.conn.commit()  except:            # 可以捕獲所有異常(django事務(wù)如果中間出現(xiàn)程序異常終止無(wú)法回滾)   try:     # 回滾本身也是sql執(zhí)行，也有可能失敗    import traceback    traceback.print_exc()    print 'rollback'    self.conn.rollback()   except:    print u'回滾失敗'  finally:   self.cur.close()   self.conn.close()

# 在事務(wù)塊中@atomic() 或者 with atomic():sid = transaction.savepoint('tbkt_pxb')try: # do ..........except: transaction.savepoint_rollback(sid, 'tbkt_pxb')

  ziyuan_app = ['math2', 'ziyuan']  if model._meta.app_label in ziyuan_app:   return "ziyuan_new"  return 'default'