I am writing code that will solve readers writers problem but when i use sem_init to initialise unnamed semaphore,
it returns -1 my code is
sem_t sem;
main()
{
int ret;
ret = sem_init(&sem, 0, 1);
printf("Return %d\n", ret);
}
Is there any mistake with my code please let me know.If not provide me with suggestions to solve this problem?
Mac mini, Mac OS X (10.6.4)
Wrong semaphore. That is a real-time API. If you check errno you will see that it says it is not implemented. Use the SYS V IPC versions like semget and semop.
@etresoft Thanks. I get my solution by sem_unlink before sem_init or sem_open
But why mac developers had done such unimplemented stuff. It becomes difficult to even get one simple
example to understand the concept or to get started?
As I said above, that is a realtime extension. OS X is not a realtime operating system and has many other concurrency APIs, pretty much all of which are better.
I am novice and i don't know much about what you are saying.
But wheather i am using wrong way for semaphores on OSX?
You are trying to use a specific, newer type of semaphore that is meant for realtime systems like VxWorks. Linux includes it too, even though Linux isn't any more realtime than OS X. The original semaphore idea belongs to Edsger Dijkstra from 1965. It really isn't used anymore in new development. The state of the art in concurrency is Apple's Grand Central Dispatch.
Mac doesn’t support unnamed semaphores
Check this::
https://heldercorreia.com/semaphores-in-mac-os-x-fd7a7418e13b
sem_init is not working on Mac OSX 10.6.4(Snow Leopard)
