From a77a2c30b1134676a676887c30b070efc467119f Mon Sep 17 00:00:00 2001
From: Nathan Fisher <jeang3nie@hitchhiker-linux.org>
Date: Mon, 31 Jul 2023 11:24:03 -0400
Subject: [PATCH] Replace semaphore with pthread_cond_t in job queue

---
 include/jobq.h | 6 ++++--
 src/jobq.c     | 9 +++++----
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/include/jobq.h b/include/jobq.h
index c00c92b..df9a0c2 100644
--- a/include/jobq.h
+++ b/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;
diff --git a/src/jobq.c b/src/jobq.c
index 4c470f5..e402dce 100644
--- a/src/jobq.c
+++ b/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;
 }