Messages in this thread | | | Date | Tue, 28 Jan 2014 10:04:02 +0100 | From | Clemens Ladisch <> | Subject | Re: WaitForMultipleObjects/etc. In Kernel |
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Network Nut wrote: > 5. I can simulate system-global named mutex using shared-memory for > underlying state of mutex (POCO NamedMutex) > 6. I can get named semaphore using POSIX sem_create > > It seems that the remaining problem is to get named mutex and named > semaphore to be accessible by file-descriptor.
Forget about the POSIX stuff. You can implement a mutex by using an eventfd that has the value 1 in the unlocked state; a read locks, a write of 1 unlocks. You can implement a semaphore by using an eventfd with EFD_SEMAPHORE.
And I should note that it is a common pattern to start a bunch of other processes from a helper process; this not only allows inheriting file descriptors, but also makes monitoring these processes easier from the parent. Do all of your processes really need to be started independently?
>>> "The timeout argument specifies the minimum number of milliseconds >>> that epoll_wait() will block." >>> >>> I think the word "minimum" should be "maximum". >> >> This sentence was copied from the poll(2) man page, where the previous >> sentence says "poll() blocks until one of the events occurs". So the word >> "block" implies that no event has occured. > > So that means that it is a bug, right? Or?
The purpose of a man page is certainly not to confuse its readers. I'd guess the maintainer would be happy about an improved wording.
Regards, Clemens
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