"Reading notes" Gcd-dispatch Queue

One, the implementation of the Dispatch queue:

1, used to manage the FIFO queue implemented by the C language layer of the appended block.

A lightweight signal for exclusive control implemented in the 2,atomic function.

3, some containers that are implemented by the C language layer for managing threads.

Second, the benefits of CGD.

No matter how hard programmers try to write code that manages threads, it is not possible to outperform the GCD implemented at the XNU kernel level in terms of performance.

Using GCD is better than using these generic multithreaded programming APIs like Pthreads and Nsthread. And, if you're using GCD, you don't have to write a similar source code that's recurring for the operation thread (this is called a fixed source snippet), and it's really a lot of benefit to be able to centralize the processing in the threads. We try to use GCD as much as possible or use APIs such as the Nsoperationqueue class GCD the cocoa framework.

Third, the GCD APIs used by programmers are all C-language functions included in the Libdispatch library. The Dispatch queue is implemented as a FIFO queue through structs and linked lists. FIFO Queue Management is a block that is appended by functions such as Dispatch_async.

Instead of joining the Fifi Queue directly, Block joins the dispatch continuation in the dispatch_continuation_t type struct and then joins the FIFO queue. The dispatch continuation is used to memorize the dispatch group and other information that the bloc belongs to, which is equivalent to the commonly used execution context.

Reference: "Objective-c advanced Programming iOS and OS X multithreading and memory Management"

  

"Reading notes" Gcd-dispatch Queue