first commit

CS4210/Readings/ProducerConsumer.c

@@ -0,0 +1,80 @@
+#include<pthread.h>
+#include <stdio.h>
+
+/* Producer/consumer program illustrating conditional variables */
+
+/* Size of shared buffer */
+#define BUF_SIZE 3
+
+int buffer[BUF_SIZE];							/* shared buffer */
+int add=0;										/* place to add next element */
+int rem=0;										/* place to remove next element */
+int num=0;										/* number elements in buffer */
+pthread_mutex_t m=PTHREAD_MUTEX_INITIALIZER;	/* mutex lock for buffer */
+pthread_cond_t c_cons=PTHREAD_COND_INITIALIZER; /* consumer waits on this cond var */
+pthread_cond_t c_prod=PTHREAD_COND_INITIALIZER; /* producer waits on this cond var */
+
+void *producer(void *param);
+void *consumer(void *param);
+
+main (int argc, char *argv[])
+{
+	pthread_t tid1, tid2;		/* thread identifiers */
+	int i;
+
+	/* create the threads; may be any number, in general */
+	if (pthread_create(&tid1,NULL,producer,NULL) != 0) {
+		fprintf (stderr, "Unable to create producer thread\n");
+		exit (1);
+	}
+	if (pthread_create(&tid2,NULL,consumer,NULL) != 0) {
+		fprintf (stderr, "Unable to create consumer thread\n");
+		exit (1);
+	}
+	/* wait for created thread to exit */
+	pthread_join(tid1,NULL);
+	pthread_join(tid2,NULL);
+	printf ("Parent quiting\n");
+}
+
+
+/* Produce value(s) */
+void *producer(void *param)
+{
+	int i;
+	for (i=1; i<=20; i++) {
+		/* Insert into buffer */
+		pthread_mutex_lock (&m);
+		if (num > BUF_SIZE) exit(1);	/* overflow */
+		while (num == BUF_SIZE)			/* block if buffer is full */
+			pthread_cond_wait (&c_prod, &m);
+		/* if executing here, buffer not full so add element */
+		buffer[add] = i;
+		add = (add+1) % BUF_SIZE;
+		num++;
+		pthread_mutex_unlock (&m);
+		pthread_cond_signal (&c_cons);
+		printf ("producer: inserted %d\n", i);  fflush (stdout);
+	}
+	printf ("producer quiting\n");  fflush (stdout);
+}
+
+/* Consume value(s); Note the consumer never terminates */
+void *consumer(void *param)
+{
+	int i;
+	while (1) {
+		pthread_mutex_lock (&m);
+		if (num < 0) exit(1);   /* underflow */
+		while (num == 0)		/* block if buffer empty */
+			pthread_cond_wait (&c_cons, &m);
+		/* if executing here, buffer not empty so remove element */
+		i = buffer[rem];
+		rem = (rem+1) % BUF_SIZE;
+		num--;
+		pthread_mutex_unlock (&m);
+		pthread_cond_signal (&c_prod);
+		printf ("Consume value %d\n", i);  fflush(stdout);
+	}
+}
+