POSIX/SYSTEM V semaphores in golang

[Shubhro Sinha]

Hi,

I wanted to use system V / POSIX  semaphores across a daemon written in go and another in C. However I find that the syscall package does not include any function related to that. Is it intentional? Is there any alternate way to use them?

-Shubhro

[Marvin Stenger]

I guess you could make use of cgo. But I'm not sure, if that is the only/best way.

[Ian Lance Taylor]

On Tue, Mar 29, 2016 at 2:09 AM, Marvin Stenger
<marvin.s...@gmail.com> wrote:
> I guess you could make use of cgo. But I'm not sure, if that is the
> only/best way.

Somebody could add support to the golang.org/x/sys/unix package.

Ian

> Am Dienstag, 29. März 2016 10:34:15 UTC+2 schrieb Shubhro Sinha:
>>
>> Hi,
>>
>> I wanted to use system V / POSIX semaphores across a daemon written in go
>> and another in C. However I find that the syscall package does not include
>> any function related to that. Is it intentional? Is there any alternate way
>> to use them?
>>
>> -Shubhro
>

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[Konstantin Khomoutov]

On Tue, 29 Mar 2016 06:25:12 -0700
Ian Lance Taylor <ia...@golang.org> wrote:

> On Tue, Mar 29, 2016 at 2:09 AM, Marvin Stenger
> <marvin.s...@gmail.com> wrote:
> > I guess you could make use of cgo. But I'm not sure, if that is the
> > only/best way.
>
> Somebody could add support to the golang.org/x/sys/unix package.

According to manual pages on my Linux system, 4 syscalls and
accompanying data types cover the whole semaphores thing.

So, this task appears to be tractable.

[Sam Whited]

On Tue, Mar 29, 2016 at 8:41 AM, Konstantin Khomoutov
<flat...@users.sourceforge.net> wrote:
> According to manual pages on my Linux system, 4 syscalls and
> accompanying data types cover the whole semaphores thing.
>
> So, this task appears to be tractable.

If you're using existing semaphores created by another process this is
true, but if you want to create your own semaphore you'll need to be
able to call sem_open(3) (for named semaphores; there are other
methods for closing, unlinking, creating unnamed semaphores, etc.).

I assume this is what he's asking about, and it would probably make
sense to stick something like that in x/sys/unix.

—Sam

A full list (I think?) would include:

- sem_open(3)
- sem_wait(3)
- sem_post(3)
- sem_close(3)
- sem_unlink(3)
- sem_init(3)
- sem_destroy(3)

--
Sam Whited
pub 4096R/54083AE104EA7AD3
https://blog.samwhited.com

[Konstantin Khomoutov]

No, the 3rd section of manual pages on Linux-based systems means
facilities provided by libraries -- either libc or other user-space
stuff. This means cgo. Go-specific code should strive to rely on
system calls only; and for x/sys/unix it is, I assume, a must except
we're talking about some "weird" platforms like Solaris (?) which must
route all calls to the kernel through libc. On Linux-based systems,
syscalls are described by the pages in the 2nd section, so here we go:

~% apropos semaphore | grep -F '(2)'
semctl (2) - System V semaphore control operations
semget (2) - get a System V semaphore set identifier
semop (2) - System V semaphore operations
semtimedop (2) - System V semaphore operations

Quick googling reveals that indeed this appears to be a rather complete
set of stuff to deal with semaphores.

[shu...@ionosnetworks.com]

I ended up using syscall.Sycall() function to call the SYS V semaphore system calls and wrapped them up in a package.

-Shubhro

[tema....@gmail.com]

Can you share this package?

Thanks

вторник, 29 марта 2016 г., 11:34:15 UTC+3 пользователь Shubhro Sinha написал:

[shubhro sinha]

https://github.com/shubhros/drunkendeluge/tree/master/semaphore

-Shubhro

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