Replace semaphore with pthread_cond_t in job queue

include/jobq.h

@@ -34,8 +34,9 @@
 #define JOBQ_H
 
 #include <pthread.h>
-#include <semaphore.h>
+#include <stddef.h>
 #include <stdlib.h>
+#include <sys/_pthreadtypes.h>
 
 #include "haggis.h"
 
@@ -53,7 +54,8 @@ struct _job_node {
 typedef struct _job_node haggis_jobq_node;
 
 typedef struct {
-    sem_t *sem;
+    pthread_cond_t *cond;
+    size_t count;
     pthread_mutex_t *mutex;
     haggis_jobq_node *head;
     haggis_jobq_node *tail;

src/jobq.c

@@ -47,16 +47,19 @@ int haggis_jobq_push(haggis_jobq *queue, haggis_job *job) {
         queue->tail->prev = new;
         queue->tail = new;
     }
+    queue->count++;
     pthread_mutex_unlock(queue->mutex);
-    return sem_post(queue->sem);
+    return 0;
 }
 
 haggis_job* haggis_jobq_pop(haggis_jobq *queue) {
     haggis_jobq_node *j;
     haggis_job *job;
 
-    sem_wait(queue->sem);
+    while (queue->count == 0)
+        pthread_cond_wait(queue->cond, queue->mutex);
     pthread_mutex_lock(queue->mutex);
+    queue->count--;
     j = queue->head;
     job = j->job;
     if (queue->tail == queue->head) {
@@ -66,7 +69,5 @@ haggis_job* haggis_jobq_pop(haggis_jobq *queue) {
     }
     free(j);
     pthread_mutex_unlock(queue->mutex);
-    if (sem_post(queue->sem) != 0)
-        return NULL;
     return job;
 }