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-rw-r--r--pgm5/prodcons.d/Makefile10
-rw-r--r--pgm5/prodcons.d/README2
-rw-r--r--pgm5/prodcons.d/prodcons.c124
3 files changed, 136 insertions, 0 deletions
diff --git a/pgm5/prodcons.d/Makefile b/pgm5/prodcons.d/Makefile
new file mode 100644
index 0000000..174975d
--- /dev/null
+++ b/pgm5/prodcons.d/Makefile
@@ -0,0 +1,10 @@
+CC=gcc
+CFLAGS=-g -Wall -D_REENTRANT
+LIBS=-lpthread
+
+prodcons: prodcons.c
+ $(CC) $(CFLAGS) -o prodcons prodcons.c $(LIBS)
+
+clean:
+ rm -f prodcons core.*
+
diff --git a/pgm5/prodcons.d/README b/pgm5/prodcons.d/README
new file mode 100644
index 0000000..3c85ac4
--- /dev/null
+++ b/pgm5/prodcons.d/README
@@ -0,0 +1,2 @@
+Producer/Consumer with a bounded buffer. From the
+linuxthreads demos.
diff --git a/pgm5/prodcons.d/prodcons.c b/pgm5/prodcons.d/prodcons.c
new file mode 100644
index 0000000..665c744
--- /dev/null
+++ b/pgm5/prodcons.d/prodcons.c
@@ -0,0 +1,124 @@
+/* The classic producer-consumer example.
+ Illustrates mutexes and conditions.
+ All integers between 0 and 9999 should be printed exactly twice,
+ once to the right of the arrow and once to the left. */
+
+#include <stdio.h>
+#include <pthread.h>
+
+#define BUFFER_SIZE 16
+
+/* Circular buffer of integers. */
+
+struct prodcons
+{
+ int buffer[BUFFER_SIZE]; /* the actual data */
+ pthread_mutex_t lock; /* mutex ensuring exclusive access to buffer */
+ int readpos, writepos; /* positions for reading and writing */
+ pthread_cond_t notempty; /* signaled when buffer is not empty */
+ pthread_cond_t notfull; /* signaled when buffer is not full */
+};
+
+/* Initialize a buffer */
+static void
+init (struct prodcons *b)
+{
+ pthread_mutex_init (&b->lock, NULL);
+ pthread_cond_init (&b->notempty, NULL);
+ pthread_cond_init (&b->notfull, NULL);
+ b->readpos = 0;
+ b->writepos = 0;
+}
+
+/* Store an integer in the buffer */
+static void
+put (struct prodcons *b, int data)
+{
+ pthread_mutex_lock (&b->lock);
+ /* Wait until buffer is not full */
+ while ((b->writepos + 1) % BUFFER_SIZE == b->readpos)
+ {
+ pthread_cond_wait (&b->notfull, &b->lock);
+ /* pthread_cond_wait reacquired b->lock before returning */
+ }
+ /* Write the data and advance write pointer */
+ b->buffer[b->writepos] = data;
+ b->writepos++;
+ if (b->writepos >= BUFFER_SIZE)
+ b->writepos = 0;
+ /* Signal that the buffer is now not empty */
+ pthread_cond_signal (&b->notempty);
+ pthread_mutex_unlock (&b->lock);
+}
+
+/* Read and remove an integer from the buffer */
+static int
+get (struct prodcons *b)
+{
+ int data;
+ pthread_mutex_lock (&b->lock);
+ /* Wait until buffer is not empty */
+ while (b->writepos == b->readpos)
+ {
+ pthread_cond_wait (&b->notempty, &b->lock);
+ }
+ /* Read the data and advance read pointer */
+ data = b->buffer[b->readpos];
+ b->readpos++;
+ if (b->readpos >= BUFFER_SIZE)
+ b->readpos = 0;
+ /* Signal that the buffer is now not full */
+ pthread_cond_signal (&b->notfull);
+ pthread_mutex_unlock (&b->lock);
+ return data;
+}
+
+/* A test program: one thread inserts integers from 1 to 10000,
+ the other reads them and prints them. */
+
+#define OVER (-1)
+
+struct prodcons buffer;
+
+static void *
+producer (void *data)
+{
+ int n;
+ for (n = 0; n < 10000; n++)
+ {
+ printf ("%d --->\n", n);
+ put (&buffer, n);
+ }
+ put (&buffer, OVER);
+ return NULL;
+}
+
+static void *
+consumer (void *data)
+{
+ int d;
+ while (1)
+ {
+ d = get (&buffer);
+ if (d == OVER)
+ break;
+ printf ("---> %d\n", d);
+ }
+ return NULL;
+}
+
+int
+main (void)
+{
+ pthread_t th_a, th_b;
+ void *retval;
+
+ init (&buffer);
+ /* Create the threads */
+ pthread_create (&th_a, NULL, producer, 0);
+ pthread_create (&th_b, NULL, consumer, 0);
+ /* Wait until producer and consumer finish. */
+ pthread_join (th_a, &retval);
+ pthread_join (th_b, &retval);
+ return 0;
+}