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#define _MULTI_THREADED
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <unistd.h>
void foo(void); /* Functions that use the TLS data */
void bar(void);
#define checkResults(string, val) { \
if (val) { \
printf("Failed with %d at %s", val, string); \
exit(1); \
} \
}
/*
Use the keyword provided by pthread.h to delcare the following variable
is thread specific, i.e. it is only visible to a specific thread,
not shared/common to all thread.
These variables are stored in thread local storage (TLS) area.
*/
__thread int TLS_data1 = 10;
__thread int TLS_data2 = 20;
__thread char TLS_data3[10];
// Sync, because it's needed apparently...
static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_mutex_t* mutex_ptr = &mutex;
static pthread_cond_t thread_state_cond = PTHREAD_COND_INITIALIZER;
static pthread_cond_t* thread_state_cond_ptr = &thread_state_cond;
static int status = 0;
#define NUMTHREADS 2
pthread_t thread[NUMTHREADS];
typedef struct {
int data1;
int data2;
} threadparm_t;
void *thread_run(void *parm)
{
int rc;
threadparm_t *gData;
pthread_mutex_lock(mutex_ptr);
if (pthread_self()==thread[0]) {
printf("Thread 1: Entered (%d/%d)\n", TLS_data1, TLS_data2);
fflush(stdout);
} else {
while (!status) pthread_cond_wait(thread_state_cond_ptr, mutex_ptr);
printf("Thread 2: Entered (%d/%d)\n", TLS_data1, TLS_data2);
fflush(stdout);
pthread_mutex_unlock(mutex_ptr);
status = 0;
pthread_cond_broadcast(thread_state_cond_ptr);
}
gData = (threadparm_t *)parm;
/* Assign the value from global variable to thread specific variable*/
TLS_data1 = gData->data1;
TLS_data2 = gData->data2;
strcpy(TLS_data3, "---");
TLS_data3[1] = (pthread_self()==thread[0])?'1':'2';
foo();
return NULL;
}
void foo() {
if (pthread_self()==thread[0]) {
printf("Thread 1: foo(), TLS data=%d %d \"%s\"\n", TLS_data1, TLS_data2, TLS_data3);
fflush(stdout);
status = 1;
pthread_cond_broadcast(thread_state_cond_ptr);
while (status) pthread_cond_wait(thread_state_cond_ptr, mutex_ptr);
pthread_mutex_unlock(mutex_ptr);
} else {
printf("Thread 2: foo(), TLS data=%d %d \"%s\"\n", TLS_data1, TLS_data2, TLS_data3);
fflush(stdout);
}
while(!thread[1])
usleep(300);
if(pthread_self()==thread[0])
pthread_join(thread[1], NULL);
bar();
}
void bar() {
printf("Thread %d: bar(), TLS data=%d %d \"%s\"\n",
(pthread_self()==thread[0])?1:2, TLS_data1, TLS_data2, TLS_data3);
fflush(stdout);
return;
}
int main(int argc, char **argv)
{
int rc=0;
int i;
threadparm_t gData[NUMTHREADS];
printf("Create/start %d threads\n", NUMTHREADS);
fflush(stdout);
for (i=0; i < NUMTHREADS; i++) {
/* Create per-thread TLS data and pass it to the thread */
gData[i].data1 = i;
gData[i].data2 = (i+1)*2;
rc = pthread_create(&thread[i], NULL, thread_run, &gData[i]);
checkResults("pthread_create()\n", rc);
}
//printf("Wait for all threads to complete, and release their resources\n");
for (i=0; i < NUMTHREADS; i++) {
rc = pthread_join(thread[i], NULL);
//checkResults("pthread_join()\n", rc);
}
thread_state_cond_ptr = NULL;
i = pthread_cond_destroy(&thread_state_cond);
checkResults("destroying cond\n", i);
mutex_ptr = NULL;
i = pthread_mutex_destroy(&mutex);
checkResults("destroying mutex\n", i);
printf("Main completed\n");
fflush(stdout);
return 0;
}
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