Implement object table API (#16)

state/task_queue.h

@@ -0,0 +1,33 @@
+#ifndef TASK_QUEUE_H
+#define TASK_QUEUE_H
+
+#include "db.h"
+#include "task.h"
+
+/* The task ID is a deterministic hash of the function ID that
+ * the task executes and the argument IDs or argument values */
+typedef unique_id task_id;
+
+/* The task instance ID is a globally unique ID generated which
+ * identifies this particular execution of the task */
+typedef unique_id task_iid;
+
+/* The node id is an identifier for the node the task is
+ * scheduled on */
+typedef unique_id node_id;
+
+/* Callback for subscribing to the task queue. The only argument this
+ * callback gets is the task_id of the. */
+typedef void (*task_queue_callback)(task_iid *task_iid, task_spec *task);
+
+/* Submit task to the global scheduler. */
+void task_queue_submit_task(db_conn *db, task_iid task_iid, task_spec *task);
+
+/* Submit task to a local scheduler based on the decision made by the global
+ * scheduler. */
+void task_queue_schedule_task(db_conn *db, task_iid task_iid, node_id node);
+
+/* Subscribe to task queue. */
+void task_queue_register_callback(db_conn *db, task_queue_callback callback);
+
+#endif