线程安全nsdictionary [英] thread safe nsdictionary

问题描述

我有一个nsdictionary从A LOT读取，在某些点并发写入A LOT。

I have an nsdictionary that gets read from A LOT and at some points concurrently written to A LOT.

为了有助于在迭代时线程安全，我复制它，迭代副本，并添加到原始。

To help make it thread safe when iterating it, I copy it, iterate the copy, and add to the original.

有时，另一个线程正在复制它，当它被添加到。是否有更好的方法让它线程安全？

Sometimes, another thread is copying it while it is being added to. Is there a better way to make it thread safe?

推荐答案

如果你有一个 NSMutableDictionary 并且需要以线程安全的方式完成操作，最简单的方法是使用 @synchronized 语句，它告诉编译器以线程安全，异常安全的方式锁定对象的访问：

If you have changes you want to make to an NSMutableDictionary and need the operations to be done in a thread-safe manner, the simplest way is to wrap all accesses on that object with the @synchronized statement, which tells the compiler to lock access to the object in a thread-safe, exception-safe fashion:

@synchronized (myDictionary) {
    [myDictionary setObject: ... forKey: ...];
    [myDictionary removeObjectForKey: ...];
}

有更高性能的替代方案 @synchronized ，但这只应该是一个问题，如果你已经剖析你的代码，并看到同步是一个问题。

There are higher-performance alternatives to @synchronized, but that should only be a concern if you've profiled your code and see synchronization is an issue.

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