refactor Queue, len check, memory pool for Node of Job, not job

src/util.zig

@@ -16,8 +16,10 @@ pub const Job = struct {
     target: *BlockQuantized,
 };
 pub const JobQueue = struct {
+    const List = std.TailQueue(Job);
+    
     mutex: std.Thread.Mutex,
-    queue: std.TailQueue(Job),
+    queue: List,
     job_pool: JobPool,
 
     const Self = @This();
@@ -26,7 +28,7 @@ pub const JobQueue = struct {
     pub fn init(pool: JobPool) Self {
         return Self {
             .mutex = std.Thread.Mutex{},
-            .queue = std.TailQueue(Job){},
+            .queue = List{},
             .job_pool = pool,
         };
     }
@@ -47,8 +49,14 @@ pub const JobQueue = struct {
         self.job_pool.destroy(n);
         return job;
     }
+
+    pub fn HasJobs(self: *Self) bool {
+        self.mutex.lock();
+        defer self.mutex.unlock();
+        return (self.queue.len == 0);
+    }
 };
-pub const JobPool = std.heap.MemoryPool(Job);
+pub const JobPool = std.heap.MemoryPool(JobQueue.List.Node);
 
 pub const Buffers = struct {
     arena: std.heap.ArenaAllocator,