我读了苹果公司的文件《同时编程指南》,我认为“行动队列”是一系列行动。 该文件说,我们在“国家业务队队队”中不使用锁。
<强问/强>
如何执行 Read & amp; Write 和 NNS OperationQuue 执行任务?
何时在NSA行动队列中使用锁?
操作队列不一定是序列队列。 您可以在队列上调用 [queue setMaxConcurporationOpertyCount:1] , 将操作队列编成序列队列。 否则, 默认的话, NS OpertyQue 是同时的 。
您一般应该设计您提交到队列的操作, 这样它们不需要锁。 这是您的责任。 想法是操作应该自成一体。 它们应该配置在提交运行前操作所需的数据。 数据应该是一个私人副本; 它不应该是操作同时访问的操作, 而其它东西也正在访问它。 操作在运行中, 它应该只使用其私人数据工作, 不应该访问程序的其他部分。 当操作完成后, 它应该将其结果提供给程序的其余部分 。 ( 这可能是被动的, 只需将结果存储在它自己的属性中即可 。 然后, 程序的其他部分, 可能已经观察到操作完成的功能可以读取它。 或者它可能是活动的, 操作最后一件事是调用其他对象, 并发送结果 。)
NS OpertyQueue 不为读写锁定提供支持。 您可以为此使用 pthread_rwlock API。 但另一种方法是使用 GCD 发送有屏障任务的队列。 使用 dispatch_ queue_ create () 创建一个私有的同步队列。 以 dispatch_ [a]sync () 向它提交读任务。 请使用 dispatch_barrier_[a]sync () 向它提交写入任务 。
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