OS signaling

#include <stdio.h> #include <errno.h> #include <stdlib.h> #include <string.h> #include <signal.h> #include "scheduler.h" /******************************************************************************* * * Implement these functions. * ******************************************************************************/ /* Handler for SIGTERM signal */ void cancel_thread() { printf("Thread %u: terminating.\n", (unsigned int)pthread_self()); /* signal that done in queue */ sem_post(&queue_sem); pthread_exit(NULL); } /* TODO: Handle the SIGUSR1 signal */ void suspend_thread() { printf("Thread %u: suspending.\n", (unsigned int)pthread_self()); /*add your code here to wait for a resume signal from the scheduler*/ printf("Thread %u: resuming.\n",(unsigned int) pthread_self()); } /******************************************************************************* * * * ******************************************************************************/ /* * waits to gain access to the scheduler queue. */ static int enter_scheduler_queue(thread_info_t *info) { /* * wait for available room in queue. * create a new list entry for this thread * store this thread info in the new entry. */ sem_wait(&queue_sem); list_elem *item = (list_elem*)malloc(sizeof(list_elem)); info->le = item; item->info = info; item->prev = 0; item->next = 0; list_insert_tail(&sched_queue, item); return 0; } /* * leaves the scheduler queue */ void leave_scheduler_queue(thread_info_t *info) { printf("Thread %lu: leaving scheduler queue.\n", info->thrid); /* * remove the given worker from queue * clean up the memory that we malloc'd for the list * clean up the memory that was passed to us */ list_remove(&sched_queue, info->le); free(info->le); free(info); } /* * Initialize thread, enter scheduling queue, and execute instructions. * arg is a pointer to thread_info_t */ void *start_worker(void *arg) { thread_info_t *info = (thread_info_t *) arg; float calc = 0.8; int j = 0; /* TODO: Block SIGALRM and SIGUSR2. */ /* TODO: Unblock SIGUSR1 and SIGTERM. */ /* compete with other threads to enter queue. */ if (enter_scheduler_queue(info)) { printf("Thread %lu: failure entering scheduler queue - %s\n", info->thrid, strerror(errno)); free (info); pthread_exit(0); } printf("Thread %lu: in scheduler queue.\n", info->thrid); suspend_thread(); while (1) { /* do some meaningless work... */ for (j = 0; j < 10000000; j++) { calc = 4.0 * calc * (1.0 - calc); } } }