Fred'ô farias06

𝗖 𝗶𝘀 𝘁𝗵𝗲 𝗺𝗼𝘀𝘁 𝗲𝗳𝗳𝗶𝗰𝗶𝗲𝗻𝘁 𝗽𝗿𝗼𝗴𝗿𝗮𝗺𝗺𝗶𝗻𝗴 𝗹𝗮𝗻𝗴𝘂𝗮𝗴𝗲, 𝘄𝗵𝗶𝗹𝗲 𝗣𝘆𝘁𝗵𝗼𝗻 𝗮𝗻𝗱 𝗣𝗲𝗿𝗹 𝗮𝗿𝗲 𝘁𝗵𝗲 𝗹𝗲𝗮𝘀𝘁 𝗲𝗻𝘃𝗶𝗿𝗼𝗻𝗺𝗲𝗻𝘁𝗮𝗹 𝗳𝗿𝗶𝗲𝗻𝗱𝗹𝘆 𝗽𝗿𝗼𝗴𝗿𝗮𝗺𝗺𝗶𝗻𝗴 𝗹𝗮𝗻𝗴𝘂𝗮𝗴𝗲

Artcile complet : https://medium.com/codex/what-are-the-greenest-programming-languages-e738774b1957

Un petit exemple vaut mieux que de grands discours, voici le source en C :

#include 
#include 
#include 
#include <sys/time.h>
#include <sys/types.h>
#include 
static long debut = 0;
void* longue_pause(void* a){
        pid_t t = getpid();
        printf("pid = %d\n",(int)t);
        printf("thread longue_pause %d debut : %ld\n",(int)pthread_self(),time(0)-debut);
        sleep(10);
        printf("thread longue_pause %d fin : %ld\n",(int)pthread_self(),time(0)-debut);
}
void* petites_pauses(void* a){
	int i = 0;
        pid_t t = getpid();
        printf("pid = %d\n",t);
        printf("thread petites_pauses %d debut : %ld \n",(int)pthread_self(), time(0)-debut);
        for(; i < 10 ;++i){
                printf("thread petites_pauses %d en cours : %ld \n",(int)pthread_self(), time(0)-debut);
                sleep(1);
        }
}
int main(){
        pthread_t longue;
        pthread_t petit1;
        pthread_t petit2;
        debut = time(0);
        pthread_create(&longue,NULL,longue_pause,NULL);
        pthread_create(&petit1,NULL,petites_pauses,NULL);
        pthread_create(&petit2,NULL,petites_pauses,NULL);
	sleep(8);
	printf("Debut join: %ld\n",time(0)-debut);
        pthread_join(longue,NULL);
        printf("fin long : %ld\n",time(0)-debut); 
        pthread_join(petit1,NULL);
	printf("fin petit1 : %ld\n",time(0)-debut);	
        pthread_join(petit2,NULL);
	printf("fin petit2 : %ld\n",time(0)-debut);
}

Pour la compilation :

Quelle misère ce portage sur une Fédora 14 :

# make
…
/usr/bin/ld: cannot find -lmysqlclient
 
# ldconfig -v | grep "mysql"
/usr/lib/mysql:
        libmysqlclient.so.16 -> libmysqlclient.so.16.0.0
        libmysqlclient_r.so.16 -> libmysqlclient_r.so.16.0.0
 
# rpm -qa | grep mysql
mysql-devel-5.1.58-1.fc14.i686
mysql-5.1.58-1.fc14.i686
mysql-libs-5.1.58-1.fc14.i686
 
# ld -lmysqlclient --verbose
GNU ld version 2.20.51.0.7-5.fc14 20100318
  Supported emulations:
   elf_i386
   i386linux
   elf_x86_64
   elf_l1om
using internal linker script:
==================================================
/* Script for -z combreloc: combine and sort reloc sections */
OUTPUT_FORMAT("elf32-i386", "elf32-i386",
              "elf32-i386")
OUTPUT_ARCH(i386)
ENTRY(_start)
SEARCH_DIR("/usr/i686-redhat-linux/lib"); SEARCH_DIR("/usr/local/lib"); SEARCH_DIR("/lib"); SEARCH_DIR("/usr/lib");
SECTIONS
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==================================================
attempt to open /usr/i686-redhat-linux/lib/libmysqlclient.so failed
attempt to open /usr/i686-redhat-linux/lib/libmysqlclient.a failed
attempt to open /usr/local/lib/libmysqlclient.so failed
attempt to open /usr/local/lib/libmysqlclient.a failed
attempt to open /lib/libmysqlclient.so failed
attempt to open /lib/libmysqlclient.a failed
attempt to open /usr/lib/libmysqlclient.so failed
attempt to open /usr/lib/libmysqlclient.a failed
 
# locate /libmysqlclient.so
/usr/lib/mysql/libmysqlclient.so
/usr/lib/mysql/libmysqlclient.so.16
/usr/lib/mysql/libmysqlclient.so.16.0.0
 
# ln -s /usr/lib/mysql/libmysqlclient.so /lib/libmysqlclient.so
 
# make
: undefined reference to `mysql_connect'
 

Ensuite il a fallu changer les fonctions mysql_connect par mysql_real_connect :