1 files changed, 212 insertions, 0 deletions
diff --git a/lab08/mutex-solution.c b/lab08/mutex-solution.c
new file mode 100644
index 0000000..9a67a32
--- /dev/null
+++ b/lab08/mutex-solution.c
@@ -0,0 +1,212 @@
+/* Example code to demonstrate behavior of multi-core, threaded application
+ *
+ * Written by:  Mike Anderson
+ *              The PTR Group, Inc.
+ *              mike@theptrgroup.com
+ *
+ * License: GPLv2
+ *
+ */
+
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <signal.h>
+
+#ifndef	TRUE
+#define	TRUE	1
+#define	FALSE	0
+#endif
+
+
+pthread_mutex_t mutex_fix;		/* protect the critical region */
+
+pthread_t looperThId;
+pthread_t conflictThId;
+
+volatile int value1;
+volatile int value2;
+volatile int counter = 0;
+volatile int bTimeToExit = FALSE;
+
+int bUseMutex = FALSE;		/* The "s" option */
+
+
+/* Conflict thread */
+void *conflictTh(void *arg)
+{
+	int same;
+	unsigned long loopCount = 0;
+	struct timespec sleep_time = {
+		.tv_sec = 0,
+		.tv_nsec = 7 * 1000 * 1000,
+	};
+
+	while (!bTimeToExit) {
+		if (bUseMutex) {
+			pthread_mutex_lock(&mutex_fix);
+		}
+
+		same = (value1 == value2);
+		if (!same)
+			printf("\nHey! value1 = %d, value2 = %d\n", value1,
+			       value2);
+
+		loopCount++;
+		if ((loopCount % 1000) == 0) {
+			printf("\nConflict thread Counter = %lu \n", loopCount);
+			fflush(stdout);
+			counter = 0;
+		}
+
+		if (bUseMutex) {
+			pthread_mutex_unlock(&mutex_fix);
+		}
+
+		/* Sleep for 7ms */
+		nanosleep(&sleep_time, NULL);
+	}
+	
+	return NULL;
+}
+
+/* Main loop thread */
+void *looperTh(void *arg)
+{
+	int counterTemp;
+	struct timespec sleep_time = {
+		.tv_sec = 0,
+		.tv_nsec = 13 * 1000 * 1000,
+	};
+
+
+	/* give the conflict thread a chance to start */
+	sleep(1);
+
+	while (!bTimeToExit) {
+		if (bUseMutex) {
+			pthread_mutex_lock(&mutex_fix);
+		}
+
+		value1 = counter;
+		value2 = counter;
+		counterTemp = counter++;
+
+		if (bUseMutex) {
+			pthread_mutex_unlock(&mutex_fix);
+		}
+
+		if ((counterTemp % 1000000) == 0) {
+			printf("Main loop counter = %d \r", counterTemp);
+			fflush(stdout);
+
+			/* Sleep for 13ms */
+			nanosleep(&sleep_time, NULL);
+		}
+	}
+	
+	return NULL;
+}
+
+/* Ctrl-C Signal Handler */
+void gotCtrlC(int sig)
+{
+	printf("\nGot Ctrl-C! Shutting down...\n");
+
+	bTimeToExit = TRUE;
+}
+
+void print_usage(char *program)
+{
+	fprintf(stderr, "Usage: %s [options]\n%s", program,
+		"-h This help\n"
+		"-s (Use mutex to enforce synchronization)\n");
+}
+
+void parse_options(int argc, char *argv[])
+{
+	int c;
+
+	opterr = 0;		/* get opt stuff */
+
+	while ((c = getopt(argc, argv, "hs")) != -1) {
+		switch (c) {
+		case 's':
+			bUseMutex = TRUE;
+			break;
+		case '?':
+			if (isprint(optopt))
+				fprintf(stderr, "Unknown option '-%c'.\n",
+					optopt);
+			else
+				fprintf(stderr,
+					"Unknown option character '\\x%x'.\n",
+					optopt);
+			/*FALLTHRU*/
+		case 'h':
+		default:
+			print_usage(argv[0]);
+			exit(EXIT_SUCCESS);
+		}
+	}
+
+	printf("Options in effect:\n");
+	if (bUseMutex)
+		printf("    Thread synchronization using mutexes is in effect \n");
+	else
+		printf("    Mutex-based thread synchronization is off \n");
+}
+
+int main(int argc, char *argv[])
+{
+	int res;
+
+	/* Parse the command line arguments */
+	parse_options(argc, argv);
+
+	printf("\nUse ^C to exit application...\n");
+
+	/* Set up the ^C signal handler so we can shut down cleanly */
+	(void)signal(SIGINT, gotCtrlC);
+
+	/* Go ahead and initialize the mutex in case we need it */
+	res = pthread_mutex_init(&mutex_fix, NULL);
+	if (res != 0) {
+		perror("Mutex initialization failed");
+		exit(EXIT_FAILURE);
+	}
+
+	/* Create the main loop thread */
+	res = pthread_create(&looperThId, NULL, looperTh, NULL);
+	if (res != 0) {
+		perror("Main loop thread creation failed");
+		exit(EXIT_FAILURE);
+	}
+
+
+	/* Create the conflict thread */
+	res = pthread_create(&conflictThId, NULL, conflictTh, NULL);
+	if (res != 0) {
+		perror("Conflict thread creation failed");
+		exit(EXIT_FAILURE);
+	}
+
+	printf("\nMain is waiting for threads to finish...\n");
+	res = pthread_join(conflictThId, NULL);
+	if (res != 0) {
+		perror("Thread join with conflictTh() failed");
+		exit(EXIT_FAILURE);
+	}
+	res = pthread_join(looperThId, NULL);
+	if (res != 0) {
+		perror("Thread join with looperTh() failed");
+		exit(EXIT_FAILURE);
+	}
+
+	printf("Threads joined -- exiting main\n");
+	pthread_mutex_destroy(&mutex_fix);
+
+	return EXIT_SUCCESS;
+}