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Re: object file memory

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Bill M wrote, On 2/7/2012 8:40 AM:
> Bill M wrote, On 2/7/2012 8:23 AM:
>> Kaz Kylheku wrote, On 2/6/2012 5:07 PM:
>>> On 2012-02-06, Bill M<wpmccormick@just_about_everywhere.com> wrote:
>>>> I have an object file foo.o that I want to link to an executable. The
>>>> main executable creates a number of child threads that use code and
>>>> variables from foo.o.
>>>
>>> Do you have the source code for foo.o that you can tweak and recompile?
>> Yes
>>>
>>>> I've included a very simplistic representation at
>>>> the end. My question is, how can each child thread (worker) get it's
>>>> own
>>>> private copy of global variables foo_char and foo_int? Or does that
>>>> just
>>>> happen auto-magically?
>>>
>>> Why would that happen automagically? It's completely the wrong thing
>>> which
>>> would break most programs.
>>>
>>>> ** foo.c **
>>>> char foo_char;
>>>> int foo_int;
>>>
>>> These are static variables, which are understood to be single-instance,
>>> and any correct program relies on them being that way. Automagically
>>> making
>>> these thread-local would be broken behavior.
>>>
>>> GCC has extensions for declaring statics thread local. Check the GCC
>>> documentation for the setion on "Thread-Local Storage", but the gist
>>> of it is:
>>>
>>> __thread char foo_char;
>>>
>>> There is also an explicit POSIX API for managing thread-specific values
>>> accessed by keys: pthread_key_create, pthread_setspecific, etc.
>>
>> So I just started reading about keys (after my original post here) and I
>> was hoping for something even easier. The GCC thread local extensions
>> seem pretty simple to implement. I give that a try first.
>>
> Perhaps I cannot mix thread local GCC extensions with p_thread's. I see
> the following errors:
>
> root@fiberio:/home/fiber/src/plccommd# make
> gcc -g -Wall -pthread -lrt -I.. -I../../include -c -o ocxclient.o
> ocxclient.c
> ocxclient.c: In function 'comm_connect':
> ocxclient.c:78: error: cannot convert to a pointer type
> ocxclient.c: In function 'start_client':
> ocxclient.c:91: warning: passing argument 1 of 'pthread_create' makes
> pointer from integer without a cast
> /usr/include/pthread.h:227: note: expected 'pthread_t * __restrict__'
> but argument is of type 'pthread_t'
>
>
> line 78:
> if(connect(sockfd, (struct sockaddr *)their_addr, sizeof(struct
> sockaddr)) == -1) {
>
> line 91:
> if ( pthread_create(client, NULL, ocx_client, server) != 0 ) {
>
Oops. Sorry, I got it:
if(connect(sockfd, (struct sockaddr *)&their_addr, sizeof(struct 
sockaddr)) == -1) {

if ( pthread_create(&client, NULL, ocx_client, server) != 0 ) {

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Thread

object file memory Bill M <wpmccormick@just_about_everywhere.com> - 2012-02-06 16:41 -0600
  Re: object file memory Kaz Kylheku <kaz@kylheku.com> - 2012-02-06 23:07 +0000
    Re: object file memory Bill M <wpmccormick@just_about_everywhere.com> - 2012-02-07 08:23 -0600
      Re: object file memory Bill M <wpmccormick@just_about_everywhere.com> - 2012-02-07 08:40 -0600
        Re: object file memory Bill M <wpmccormick@just_about_everywhere.com> - 2012-02-07 08:58 -0600
      Re: object file memory Bill M <wpmccormick@just_about_everywhere.com> - 2012-02-07 11:21 -0600
        Re: object file memory "Ersek, Laszlo" <lacos@caesar.elte.hu> - 2012-02-07 22:09 +0100
          Re: object file memory Bill M <wpmccormick@just_about_everywhere.com> - 2012-02-07 16:08 -0600
            Re: object file memory Bill M <wpmccormick@just_about_everywhere.com> - 2012-02-08 20:42 -0600
              Re: object file memory Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-02-09 19:00 +0000
            Re: object file memory Joe Beanfish <joe@nospam.duh> - 2012-02-09 11:15 -0500

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