CS代考 * critical.c

* critical.c
* Demonstrate use of mutual exclusion using mutexes
* Upper case output indicates critical output
* lower case output indicates non-critical output

Copyright By PowCoder代写 加微信 powcoder

* compile with
gcc critical.c -o critical -lrt -lpthread
#define _GNU_SOURCE
#define _REENTRANT /* macro to ensure system calls are reentrant */
#include /* header file for pthreads */
#include /* header file for POSIX conformance */
#include /* header file for POSIX time management */
#include /* header file for POSIX scheduling */
#include /* header file for standard input/outputlibrary */

pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER; /*define mutex */

void *threadA(void *); /* predefine threadA routine */
void *threadB(void *); /* predefine threadB routine */

pthread_t threadA_id,threadB_id,main_id; /* thread identifiers */
pthread_attr_t attrA,attrB; /* thread attribute structures */
struct sched_param param; /* scheduling structure for thread attributes */

int policy=SCHED_FIFO;
int priority_min,priority_max; /* for range of priority levels */

/* main routine */
int main()
int status; /* check that system calls return ok */

/* Set processor affinity */
cpu_set_t mask; CPU_ZERO(&mask); CPU_SET(0,&mask); /* use only 1 CPU core */
unsigned int len = sizeof(mask);
status = sched_setaffinity(0, len, &mask);
if (status < 0) perror("sched_setaffinity"); status = sched_getaffinity(0, len, &mask); if (status < 0) perror("sched_getaffinity"); /* Find priority limits */ priority_max = sched_get_priority_max(policy); priority_min = sched_get_priority_min(policy); /* Set priority and policy of main thread */ main_id = pthread_self(); param.sched_priority=priority_min; status = pthread_setschedparam(main_id, policy, &param); if (status != 0) perror("pthread_setschedparam"); /* error check */ /* Create threadA */ param.sched_priority = priority_min; pthread_attr_init(&attrA); status = pthread_attr_setschedpolicy(&attrA,policy); if (status != 0) perror("pthread_attr_setschedpolicy"); /* error check */ status = pthread_attr_setschedparam(&attrA,&param); if (status != 0) perror("pthread_attr_setschedparam"); /* error check */ status = pthread_create(&threadA_id, &attrA, threadA, NULL); if (status != 0) perror("pthread_create"); /* error check */ status = pthread_setschedparam(threadA_id,policy,&param); if (status != 0) perror("pthread_setschedparam"); /* Create threadB */ param.sched_priority = priority_min; pthread_attr_init(&attrB); status = pthread_attr_setschedpolicy(&attrB,policy); if (status != 0) perror("pthread_attr_setschedpolicy"); /* error check */ status = pthread_attr_setschedparam(&attrB,&param); if (status != 0) perror("pthread_attr_setschedparam"); /* error check */ status = pthread_create(&threadB_id, &attrB, threadB, NULL); if (status != 0) perror("pthread_create"); /* error check */ status = pthread_setschedparam(threadB_id,policy,&param); if (status != 0) perror("pthread_setschedparam"); /* Join threads - force main to wait for the thread to terminate */ status = pthread_join(threadA_id, NULL); if (status != 0) perror("pthread_join(threadA_id, NULL)"); /* error check */ status = pthread_join(threadB_id, NULL); if (status != 0) perror("pthread_join(threadB_id, NULL)"); /* error check */ status = pthread_mutex_destroy(&mtx); /* delete mutex */ if (status != 0) perror("pthread_mutex_destroy"); /* error check */ printf("\n"); return(0); } /* end of main */ void *threadA(void *arg) int status; /* check that system calls return ok */ for(j=1;j<=5;j++){ printf("a"); /* non -critical */ /* lock to enter critical region */ /* status = pthread_mutex_lock(&mtx); if (status != 0) perror("pthread_mutex_lock");*/ /* error check */ for(j=1;j<=5;j++){ printf("A"); /* critical */ /* increment priority of threadB above threadA */ param.sched_priority++; status = pthread_setschedparam(threadB_id,policy,&param); if (status != 0) perror("pthread_setschedparam"); /* error check */ for(j=1;j<=5;j++){ printf("A"); /* critical */ /* unlock critical region */ /* status = pthread_mutex_unlock(&mtx); if (status != 0) perror("pthread_mutex_unlock");*/ /* error check */ for(j=1;j<=5;j++){ printf("a"); /* non -critical */ return (NULL); void *threadB(void *arg) int status; /* check that system calls return ok */ for(j=1;j<=5;j++){ printf("b"); /* non -critical */ /* lock to enter critical region */ /* status = pthread_mutex_lock(&mtx); if (status != 0) perror("pthread_mutex_lock");*/ /* error check */ for(j=1;j<=5;j++){ printf("B"); /* critical */ /* increment priority of threadA to above threadB*/ param.sched_priority++; status = pthread_setschedparam(threadA_id,policy,&param); if (status != 0) perror("pthread_setschedparam"); /* error check */ for(j=1;j<=5;j++){ printf("B"); /* critical */ /* unlock critical region */ /* status = pthread_mutex_unlock(&mtx); if (status != 0) perror("pthread_mutex_unlock");*/ /* error check */ for(j=1;j<=5;j++){ printf("b"); /* non -critical */ return (NULL); 程序代写 CS代考 加微信: powcoder QQ: 1823890830 Email: powcoder@163.com