Implement LuaExtraArgs

luprex/cpp/core/luasnap.cpp

@@ -33,10 +33,17 @@ void LuaSnap::serialize(StreamBuffer *sb) {
     // Lua stack should be empty.
     assert(lua_gettop(state_) == 0);
 
-    // lua variables that we'll need.
-    LuaVar key, value;
-    LuaRet permstable, regcopy;
-    LuaDefStack LS(state_, permstable, regcopy, key, value);
+    // We'll allocate stack slots manually, to ensure
+    // that the thread serializes as we expect it to.
+    lua_pushnil(state_); // permstable
+    lua_pushnil(state_); // regcopy
+    lua_pushnil(state_); // key
+    lua_pushnil(state_); // value
+    LuaSpecial permstable(1);
+    LuaSpecial regcopy(2);
+    LuaSpecial key(3);
+    LuaSpecial value(4);
+    LuaCoreStack LS(state_);
 
     // Construct a copy of the registry table.
     LS.set(regcopy, LuaNewTable);
@@ -62,10 +69,8 @@ void LuaSnap::serialize(StreamBuffer *sb) {
     LS.rawget(permstable, LuaRegistry, "persist");
     assert(LS.istable(permstable));
 
-    // When we call 'LS.result', this should leave the
-    // permstable and the regcopy on the stack.
-    LS.result();
-    assert(lua_gettop(state_) == 2);
+    // Remove key and value from stack, leaving permstable and regcopy.
+    lua_settop(state_, 2);
 
     // Write dummy length, use eris to write data, then overwrite length.
     sb->write_int64(0);
@@ -88,13 +93,17 @@ void LuaSnap::deserialize(StreamBuffer *sb) {
     lua_pushstring(state_, "unpersist");
     lua_rawget(state_, LUA_REGISTRYINDEX);
     eris_undump(state_, sb->lua_reader, ud);
+
+    // Set up a stack frame manually.  Eris deserialization
+    // should have left permstable and regcopy on the stack.
     assert(lua_gettop(state_) == 2);
-
-    // Set up a stack frame.
-    LuaArg permstable, regcopy;
-    LuaVar key, value;
-    LuaDefStack LS(state_, permstable, regcopy, key, value);
-
+    LuaSpecial permstable(1);
+    LuaSpecial regcopy(2);
+    lua_pushnil(state_);
+    lua_pushnil(state_);
+    LuaSpecial key(3);
+    LuaSpecial value(4);
+    LuaCoreStack LS(state_);
     assert(LS.istable(regcopy));
 
     // Copy the contents of the snapshot over to the registry.
@@ -102,8 +111,7 @@ void LuaSnap::deserialize(StreamBuffer *sb) {
     while (LS.next(regcopy, key, value) != 0) {
         LS.rawset(LuaRegistry, key, value);
     }
-    LS.result();
-    assert(lua_gettop(state_) == 0);
+    lua_settop(state_, 0);
 }
 
 // Snapshot and rollback can trivially be implemented on top of serialize and