first pass at asynchronous file streaming -> hash store layer; fix non-windowed memory access in watch window when doing change visualization, causing major performance regression with large arrays; fix some extra jank with truncated-string-hover & help labels

src/file_stream/file_stream.h

@@ -0,0 +1,84 @@
+// Copyright (c) 2024 Epic Games Tools
+// Licensed under the MIT license (https://opensource.org/license/mit/)
+
+#ifndef FILE_STREAM_H
+#define FILE_STREAM_H
+
+////////////////////////////////
+//~ rjf: Per-Path Info Cache Types
+
+typedef struct FS_Node FS_Node;
+struct FS_Node
+{
+  FS_Node *next;
+  String8 path;
+  U64 timestamp;
+  U64 last_time_requested_us;
+};
+
+typedef struct FS_Slot FS_Slot;
+struct FS_Slot
+{
+  FS_Node *first;
+  FS_Node *last;
+};
+
+typedef struct FS_Stripe FS_Stripe;
+struct FS_Stripe
+{
+  Arena *arena;
+  OS_Handle cv;
+  OS_Handle rw_mutex;
+};
+
+////////////////////////////////
+//~ rjf: Shared State Bundle
+
+typedef struct FS_Shared FS_Shared;
+struct FS_Shared
+{
+  Arena *arena;
+  
+  // rjf: path info cache
+  U64 slots_count;
+  U64 stripes_count;
+  FS_Slot *slots;
+  FS_Stripe *stripes;
+  
+  // rjf: user -> streamer ring buffer
+  U64 u2s_ring_size;
+  U8 *u2s_ring_base;
+  U64 u2s_ring_write_pos;
+  U64 u2s_ring_read_pos;
+  OS_Handle u2s_ring_cv;
+  OS_Handle u2s_ring_mutex;
+  
+  // rjf: streamer threads
+  U64 streamer_count;
+  OS_Handle *streamers;
+};
+
+////////////////////////////////
+//~ rjf: Globals
+
+global FS_Shared *fs_shared = 0;
+
+////////////////////////////////
+//~ rjf: Top-Level API
+
+internal void fs_init(void);
+
+////////////////////////////////
+//~ rjf: Cache Interaction
+
+internal U128 fs_hash_from_path(String8 path, U64 rewind_count, U64 endt_us);
+
+////////////////////////////////
+//~ rjf: Streamer Threads
+
+internal B32 fs_u2s_enqueue_path(String8 path, U64 endt_us);
+internal String8 fs_u2s_dequeue_path(Arena *arena);
+
+internal void fs_streamer_thread__entry_point(void *p);
+
+#endif // FILE_STREAM_H