From a1f91d62c35604c8d5498cc15c1b4d98cd712ec7 Mon Sep 17 00:00:00 2001
From: Robert Gustafsson <robg@student.chalmers.se>
Date: Fri, 29 Sep 2017 15:04:25 +0200
Subject: Add blocking wait when buffer is empty

---
 broccoli/fifoqueue.c   | 17 +++++++++++------
 broccoli/midbropasad.c |  3 ++-
 2 files changed, 13 insertions(+), 7 deletions(-)

(limited to 'broccoli')

diff --git a/broccoli/fifoqueue.c b/broccoli/fifoqueue.c
index 6676484..dfb8464 100644
--- a/broccoli/fifoqueue.c
+++ b/broccoli/fifoqueue.c
@@ -2,6 +2,7 @@
 #include <pthread.h>
 
 pthread_mutex_t lock;
+pthread_mutex_t bufferEmptyBlock;
 
     Fifo_q * 
 init_queue(int size)
@@ -11,11 +12,15 @@ init_queue(int size)
     q->tail = NULL;
     q->maxSize = size;
     q->currentSize = 0;
-
     if (pthread_mutex_init(&lock, NULL) != 0)
     {
         printf("WARNING: Couldn't initialize lock\n");
     }
+    if (pthread_mutex_init(&bufferEmptyBlock, NULL) != 0)
+    {
+        printf("WARNING: Couldn't initialize blocking lock\n");
+    }
+    pthread_mutex_lock(&bufferEmptyBlock);
     return q;
 }
 
@@ -52,14 +57,14 @@ add_to_queue(Fifo_q * q, Sensor_t * sensor)
     Queue_t * new_elem = (Queue_t *) malloc(sizeof(Queue_t *));
     new_elem->next = NULL;
     new_elem->sensor = sensor;
-    if(is_empty(q))
+    if(is_empty(q)){
         q->head = new_elem;
-    else
+        pthread_mutex_unlock(&bufferEmptyBlock);
+    }else
         q->tail->next = new_elem;
     q->tail = new_elem;
     q->currentSize++;
     pthread_mutex_unlock(&lock);
-    print_queue(q);
     return 1;
 }
 
@@ -67,11 +72,11 @@ add_to_queue(Fifo_q * q, Sensor_t * sensor)
 pop_from_queue(Fifo_q * q)
 {
 
-    pthread_mutex_lock(&lock);
     if(is_empty(q)){
         perror("The queue is empty");
-        exit(-1);
+        pthread_mutex_lock(&bufferEmptyBlock);
     }
+    pthread_mutex_lock(&lock);
     Queue_t * head = q->head;
     q->head = q->head->next;
     Sensor_t * sensor = head->sensor;
diff --git a/broccoli/midbropasad.c b/broccoli/midbropasad.c
index 6db59a5..70a290f 100644
--- a/broccoli/midbropasad.c
+++ b/broccoli/midbropasad.c
@@ -20,7 +20,8 @@ main(int argc, char **argv)
     start_data_capture(q);
     while(true){
         printf("Main thread\n");
-        sleep(2);
+        sleep(10);
+        print_queue(q);
     }
     free(q);
     return 0;
-- 
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