Remove BTech persistence preload shim

Author: gtaylor

src/btech/persistence/btech_persistence_sqlite.c

@@ -3685,7 +3685,7 @@ static void btech_store_repair_event(MuxEvent *event, void *context_argument) {
     context->result = -1;
 }
 
-/* Mirror map dynamic state and repair queues without changing legacy reads. */
+/* Store map dynamic state and repair queues in the SQLite snapshot. */
 static int btech_persistence_store_special_state(
     sqlite3 *sqlite, PersistenceContext *persistence, void *extension_context) {
   BtechContext *btech = extension_context;
@@ -3861,15 +3861,6 @@ static int btech_persistence_store_special_state(
   return result;
 }
 
-/* Reads remain on the legacy files during this first BTech dual-write slice. */
-static int btech_persistence_preload_special_state(
-    sqlite3 *sqlite, PersistenceContext *persistence, void *extension_context) {
-  (void)persistence;
-  (void)extension_context;
-  (void)sqlite;
-  return 0;
-}
-
 typedef struct btech_special_object_counts BTECH_SPECIAL_OBJECT_COUNTS;
 struct btech_special_object_counts {
   int maps;
@@ -4313,8 +4304,7 @@ static int btech_persistence_store_economy(sqlite3 *sqlite,
 int btech_persistence_register(PersistenceContext *context,
                                BtechContext *btech) {
   if (persistence_register_sqlite_extension(
-          context, "btech_special_state",
-          btech_persistence_preload_special_state,
+          context, "btech_special_state", nullptr,
           btech_persistence_store_special_state, btech) < 0)
     return -1;
 #ifdef BT_ADVANCED_ECON

src/mux/persistence/commac_persistence_sqlite.c

@@ -17,8 +17,7 @@
 #include "mux/server/server_config.h"
 #include "mux/support/utf8.h"
 
-/* The legacy file is read during this phase; SQLite is an atomic dump mirror.
- */
+/* SQLite schema for commac, comsys, and macro state. */
 static const char commac_schema_sql[] =
     "CREATE TABLE commac_entries ("
     " who INTEGER PRIMARY KEY, curmac INTEGER NOT NULL,"

src/mux/persistence/gamedb.h

@@ -61,8 +61,10 @@ void persistence_context_initialize(
 /*
  * Register a named SQLite extension before gamedb_load() or gamedb_dump().
  * The callbacks are invoked with the SQLite connection owned by this module;
- * store callbacks run inside the snapshot transaction. Returns 0 on success
- * and -1 if the registration is invalid or the extension limit is reached.
+ * store callbacks run inside the snapshot transaction. A load callback may be
+ * nullptr when the subsystem restores its data after core loading. Returns 0
+ * on success and -1 if the registration is invalid or the extension limit is
+ * reached.
  */
 int persistence_register_sqlite_extension(PersistenceContext *context,
                                           const char *name,

src/mux/persistence/gamedb_sqlite.c

@@ -212,6 +212,8 @@ static int gamedb_load_extensions(PersistenceContext *context, sqlite3 *sqlite,
 
   for (index = 0; index < context->extension_count; index++) {
     PersistenceSqliteExtension *extension = &context->extensions[index];
+    if (extension->load == nullptr)
+      continue;
     if (extension->load(sqlite, context, extension->context) < 0) {
       gamedb_log_extension_failure(context->log, "loading", extension->name,
                                    path, sqlite);

src/mux/persistence/persistence_registry.c

@@ -28,7 +28,7 @@ int persistence_register_sqlite_extension(PersistenceContext *context,
                                           void *extension_context) {
   assert(context != nullptr);
 
-  if (name == nullptr || *name == '\0' || load == nullptr || store == nullptr)
+  if (name == nullptr || *name == '\0' || store == nullptr)
     return -1;
   for (size_t index = 0; index < context->extension_count; index++) {
     PersistenceSqliteExtension *extension = &context->extensions[index];

tests/gamedb_integration.c

@@ -37,8 +37,7 @@ static int run_server(const char *binary_path, const char *config,
   return waitpid(child, status, 0) == child ? 0 : -1;
 }
 
-/* Run an isolated server instance so legacy dual-write artifacts stay
- * disposable. */
+/* Run an isolated server instance so snapshot artifacts stay disposable. */
 static int run_server_in_directory_for(const char *binary_path,
                                        const char *config,
                                        const char *directory, int make_minimal,