Re: Semaphore

• Subject: Re: Semaphore
• From: Luke Hiesterman <email@hidden>
• Date: Sun, 30 Nov 2008 20:18:00 -0800
• Delivered-to: email@hidden
• Delivered-to: email@hidden

Luke

Sent from my iPhone.

Yes that is my query what path to choose to make sure that it would
generate same key in both dylib and app.

regards

On Mon, Dec 1, 2008 at 9:16 AM, Luke Hiesterman <email@hidden> wrote:

If you use the same path and same id for ftok on both processes then you
will get the same key for use with semget. This is precisely the purpose of
ftok.

Luke

Sent from my iPhone.

On Nov 30, 2008, at 7:15 PM, Rakesh Singhal <email@hidden>
wrote:

Thanks. The problem I have to give file path to generate key. How will
I ensure that the path I am giving will work always to generate the
same key? I have one application and another is dynamic library and I
want to generate the same key in both to use.

Regards
rksinghal

On Mon, Dec 1, 2008 at 12:56 AM, Luke Hiesterman <email@hidden>
wrote:

Why exactly do you want to avoid ftok? It's a good way to generate shared
keys.

It's always possible to generate an integer key some other way yourself
and
then you just have to figure out how to communicate it across processes.
You
could write it to a file or send it over a socket.

Luke

Sent from my iPhone.

On Nov 30, 2008, at 3:25 AM, Rakesh Singhal <email@hidden >
wrote:

Is it possible to use semget() without using ftok() for IPC
communication?

Please suggest me.

Regards
rksinghal

On Fri, Nov 28, 2008 at 9:54 AM, Rakesh Singhal
<email@hidden> wrote:

Thanks. Now I am using following set of APIs:

ftok()
semget()
semop()
semctl()

It is working till now :)

Regards
rksinghal

On Thu, Nov 27, 2008 at 9:49 AM, Terry Lambert <email@hidden >
wrote:

On Nov 26, 2008, at 7:31 PM, Rakesh Singhal wrote:

Hi all

I tried to use sem_init() but I think it is not there to use. It is
declared in semaphore.h but when I do man sem_init() then it gives
the
message "No manual entry for sem_init".

Now, I am using sem_open(). I think it is right API to create unique
semaphore between multi-processes. But creating it in one process if
I
try to create in another process, the value of semaphore is not same.
I am using same name in both process(1st argument of sem_open()).

Please suggest to create semaphore (cross-processes).

POSIX unnamed semaphores are not supported.

Use either POSIX named semaphores, or use System V semaphores:

  man sem_open
  man semget

-- Terry

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