Add proto full name support for tracing.

Creates a tracing helper function to associate mini tables with proto full names to use for upcoming upb metrics collectors.

PiperOrigin-RevId: 613290255

upb/mini_table/internal/message.h

@@ -57,11 +57,16 @@ struct upb_MiniTable {
   uint8_t UPB_PRIVATE(dense_below);
   uint8_t UPB_PRIVATE(table_mask);
   uint8_t UPB_PRIVATE(required_count);  // Required fields have the low hasbits.
+#ifdef UPB_TRACING_ENABLED
+  const char* UPB_PRIVATE(full_name);
+#endif
 
+#ifdef UPB_FASTTABLE_ENABLED
   // To statically initialize the tables of variable length, we need a flexible
   // array member, and we need to compile in gnu99 mode (constant initialization
   // of flexible array members is a GNU extension, not in C99 unfortunately.
   _upb_FastTable_Entry UPB_PRIVATE(fasttable)[];
+#endif
 };
 // LINT.ThenChange(//depot/google3/third_party/upb/bits/typescript/mini_table.ts)
 
@@ -154,6 +159,13 @@ UPB_PRIVATE(_upb_MiniTable_RequiredMask)(const struct upb_MiniTable* m) {
   return (1ULL << n) - 1;
 }
 
+#ifdef UPB_TRACING_ENABLED
+UPB_INLINE const char* upb_MiniTable_FullName(
+    const struct upb_MiniTable* mini_table) {
+  return mini_table->UPB_PRIVATE(full_name);
+}
+#endif
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif

upb/port/def.inc

@@ -344,3 +344,9 @@ void __asan_unpoison_memory_region(void const volatile *addr, size_t size);
 #define UPB_DESC(sym) google_protobuf_##sym
 #define UPB_DESC_MINITABLE(sym) &google__protobuf__##sym##_msg_init
 #endif
+
+#ifdef UPB_TRACING_ENABLED
+#ifdef NDEBUG
+error UPB_TRACING_ENABLED Tracing should be disabled in production builds
+#endif
+#endif

upb/test/BUILD

@@ -68,6 +68,7 @@ proto_library(
     name = "test_proto",
     testonly = 1,
     srcs = ["test.proto"],
+    visibility = ["//upb:__subpackages__"],
 )
 
 upb_minitable_proto_library(

upb_generator/protoc-gen-upb_minitable.cc

@@ -339,6 +339,7 @@ void WriteMessage(upb::MessageDefPtr message, const DefPoolPair& pools,
   const upb_MiniTable* mt_64 = pools.GetMiniTable64(message);
   std::map<int, std::string> subs;
 
+  // Construct map of sub messages by field number.
   for (int i = 0; i < mt_64->UPB_PRIVATE(field_count); i++) {
     const upb_MiniTableField* f = &mt_64->UPB_PRIVATE(fields)[i];
     uint32_t index = f->UPB_PRIVATE(submsg_index);
@@ -349,7 +350,7 @@ void WriteMessage(upb::MessageDefPtr message, const DefPoolPair& pools,
       ABSL_CHECK(pair.second);
     }
   }
-
+  // Write upb_MiniTableSub table for sub messages referenced from fields.
   if (!subs.empty()) {
     std::string submsgs_array_name = msg_name + "_submsgs";
     submsgs_array_ref = "&" + submsgs_array_name + "[0]";
@@ -365,6 +366,7 @@ void WriteMessage(upb::MessageDefPtr message, const DefPoolPair& pools,
     output("};\n\n");
   }
 
+  // Write upb_MiniTableField table.
   if (mt_64->UPB_PRIVATE(field_count) > 0) {
     std::string fields_array_name = msg_name + "__fields";
     fields_array_ref = "&" + fields_array_name + "[0]";
@@ -407,6 +409,9 @@ void WriteMessage(upb::MessageDefPtr message, const DefPoolPair& pools,
          mt_64->UPB_PRIVATE(field_count), msgext,
          mt_64->UPB_PRIVATE(dense_below), table_mask,
          mt_64->UPB_PRIVATE(required_count));
+  output("#ifdef UPB_TRACING_ENABLED\n");
+  output("  \"$0\",\n", message.full_name());
+  output("#endif\n");
   if (!table.empty()) {
     output("  UPB_FASTTABLE_INIT({\n");
     for (const auto& ent : table) {