呼叫“旋转”是什么意思

Question

What does it mean for a function call to "spin?" Is it the same as blocking?

This is the context I'm referring to:

/*
     * Obtain a free channel
     * This call spins till a free channel is obtained
     */
    chNum = _getFreeChannel(&tccNum);

Thanks.

Answer 1

To loop, basically. What a spinning function does is busy-waiting with a loop.

Answer 2

A spin is a concurrency technique. Essentially the function loops until the desired condition is met.

It can be computationally expensive if the spin time is large, but can be preferable to wait and notification idioms (for which there is a set-up overhead) if the expected spin time is very small with low variance.

Answer 3

When a Function spins, it is typically checking some condition (like a variable) over and over in a tight loop until it becomes some interesting value. It then continues running once the condition is met.