extend task system with thread count, so usage code can easily create per-thread state; pass thread idx into task entry points

src/task_system/task_system.c

@@ -49,6 +49,15 @@ ts_init(void)
   }
 }
 
+////////////////////////////////
+//~ rjf: Top-Level Accessors
+
+internal U64
+ts_thread_count(void)
+{
+  return ts_shared->task_threads_count;
+}
+
 ////////////////////////////////
 //~ rjf: High-Level Task Kickoff / Joining
 
@@ -190,7 +199,7 @@ ts_task_thread__entry_point(void *p)
     }
     
     //- rjf: run task
-    void *task_result = task_function(task_arena, task_params);
+    void *task_result = task_function(task_arena, thread_idx, task_params);
     
     //- rjf: store into artifact
     U64 artifact_num = task_ticket.u64[0];

src/task_system/task_system.h

@@ -34,7 +34,8 @@ struct TS_TicketList
 ////////////////////////////////
 //~ rjf: Task Request Types
 
-typedef void *TS_TaskFunctionType(Arena *arena, void *user_data);
+#define TS_TASK_FUNCTION_DEF(name) void *name(Arena *arena, U64 thread_idx, void *p)
+typedef TS_TASK_FUNCTION_DEF(TS_TaskFunctionType);
 
 ////////////////////////////////
 //~ rjf: Task Artifact Cache Types
@@ -118,6 +119,11 @@ internal void ts_ticket_list_push(Arena *arena, TS_TicketList *list, TS_Ticket t
 
 internal void ts_init(void);
 
+////////////////////////////////
+//~ rjf: Top-Level Accessors
+
+internal U64 ts_thread_count(void);
+
 ////////////////////////////////
 //~ rjf: High-Level Task Kickoff / Joining