feat: implement concurrent worker queue

include/lnm/loop.h

@@ -1,6 +1,7 @@
 #ifndef LNM_LOOP
 #define LNM_LOOP
 
+#include <pthread.h>
 #include <stdatomic.h>
 #include <stdint.h>
 #include <stdlib.h>
@@ -51,4 +52,35 @@ lnm_err lnm_loop_setup(lnm_loop *l, uint16_t port);
 
 lnm_err lnm_loop_run(lnm_loop *l, int thread_count);
 
+/**
+ * Concurrent fixed-size queue used by the worked threads to distribute tasks
+ */
+typedef struct lnm_loop_queue {
+  struct {
+    lnm_loop_conn **arr;
+    size_t len;
+  } buf;
+  size_t head;
+  size_t tail;
+  pthread_mutex_t mutex;
+  pthread_cond_t cond;
+} lnm_loop_queue;
+
+/**
+ * Initialize a new queue with the specified fixed capacity
+ */
+lnm_err lnm_loop_queue_init(lnm_loop_queue **out, size_t cap);
+
+/**
+ * Queue the given connection. If the queue is currently full, this action
+ * blocks until there is space available.
+ */
+void lnm_loop_queue_push(lnm_loop_queue *q, lnm_loop_conn *conn);
+
+/**
+ * Pop a connection from the queue. This action blocks until a connection is
+ * available.
+ */
+lnm_loop_conn *lnm_loop_queue_pop(lnm_loop_queue *q);
+
 #endif