问题描述
我有一个网络应用程序,我希望能够跟踪在请求(即线程)中调用给定函数的次数.
I have a web app where i want to be able to track the number of times a given function is called in a request (i.e. thread).
我知道可以使用 ref 以非线程本地方式进行操作,但是我将如何在本地进行线程操作?
I know that it is possible to do in a non-thread local way with a ref, but how would I go about doing it thread locally?
推荐答案
有用 称为 thread-local
.例如,您可以编写 (def counter (thread-local (atom 0)))
.这将创建一个全局变量,当 deref
ed 时,将为每个线程产生一个新的原子.所以你可以用 @@counter
读取当前值,或者用 (swap!@counter inc)
增加它.当然,你也可以用 @counter
来获取原子本身,然后把它当作一个普通的原子.
There's a tool for this in useful called thread-local
. You can write, for example, (def counter (thread-local (atom 0)))
. This will create a global variable which, when deref
ed, will yield a fresh atom per thread. So you could read the current value with @@counter
, or increment it with (swap! @counter inc)
. Of course, you could also get hold of the atom itself with @counter
and just treat it like a normal atom from then on.
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