unify async task kickoff/await mechanism in first pass of 'task system' layer; use in organizing various independent parsing passes of a pdb; also fix busted multithreaded fwd resolution pass

src/task_system/task_system.h

@@ -0,0 +1,113 @@
+// Copyright (c) 2024 Epic Games Tools
+// Licensed under the MIT license (https://opensource.org/license/mit/)
+
+#ifndef TASK_SYSTEM_H
+#define TASK_SYSTEM_H
+
+////////////////////////////////
+//~ rjf: Task "Ticket" Type
+//
+// "Tickets" are opaque handles, used to refer to submitted tasks.
+//
+
+typedef struct TS_Ticket TS_Ticket;
+struct TS_Ticket
+{
+  U64 u64[2];
+};
+
+////////////////////////////////
+//~ rjf: Task Request Types
+
+typedef void *TS_TaskFunctionType(Arena *arena, void *user_data);
+
+////////////////////////////////
+//~ rjf: Task Artifact Cache Types
+
+typedef struct TS_TaskArtifact TS_TaskArtifact;
+struct TS_TaskArtifact
+{
+  TS_TaskArtifact *next;
+  U64 num;
+  B64 task_is_done;
+  void *result;
+};
+
+typedef struct TS_TaskArtifactSlot TS_TaskArtifactSlot;
+struct TS_TaskArtifactSlot
+{
+  TS_TaskArtifact *first;
+  TS_TaskArtifact *last;
+};
+
+typedef struct TS_TaskArtifactStripe TS_TaskArtifactStripe;
+struct TS_TaskArtifactStripe
+{
+  Arena *arena;
+  OS_Handle cv;
+  OS_Handle rw_mutex;
+  TS_TaskArtifact *free_artifact;
+};
+
+////////////////////////////////
+//~ rjf: Per-Thread State
+
+typedef struct TS_TaskThread TS_TaskThread;
+struct TS_TaskThread
+{
+  Arena *arena;
+  OS_Handle thread;
+};
+
+////////////////////////////////
+//~ rjf: Main Shared State
+
+typedef struct TS_Shared TS_Shared;
+struct TS_Shared
+{
+  Arena *arena;
+  
+  // rjf: task artifact cache
+  U64 artifact_num_gen;
+  U64 artifact_slots_count;
+  U64 artifact_stripes_count;
+  TS_TaskArtifactSlot *artifact_slots;
+  TS_TaskArtifactStripe *artifact_stripes;
+  
+  // rjf: task ring buffer
+  U64 u2t_ring_size;
+  U8 *u2t_ring_base;
+  U64 u2t_ring_write_pos;
+  U64 u2t_ring_read_pos;
+  OS_Handle u2t_ring_mutex;
+  OS_Handle u2t_ring_cv;
+  
+  // rjf: task threads
+  TS_TaskThread *task_threads;
+  U64 task_threads_count;
+};
+
+////////////////////////////////
+//~ rjf: Globals
+
+global TS_Shared *ts_shared = 0;
+
+////////////////////////////////
+//~ rjf: Top-Level Layer Initialization
+
+internal void ts_init(void);
+
+////////////////////////////////
+//~ rjf: High-Level Task Kickoff / Joining
+
+internal TS_Ticket ts_kickoff(TS_TaskFunctionType *entry_point, void *p);
+internal void *ts_join(TS_Ticket ticket, U64 endt_us);
+#define ts_join_struct(ticket, endt_us, type) (type *)ts_join((ticket), (endt_us))
+
+////////////////////////////////
+//~ rjf: Task Threads
+
+internal void ts_u2t_dequeue_task(TS_TaskFunctionType **entry_point_out, void **p_out, TS_Ticket *ticket_out);
+internal void ts_task_thread__entry_point(void *p);
+
+#endif // TASK_SYSTEM_H