mORMot Open Source

warleyalex

Member

From: Sete Lagoas-MG, Brasil

Registered: 2013-01-20

Posts: 250

My mORMot game

I'm developing a simple game server with a server side part written in mORMot that serve and shuffle cards, and front end written in SmartMS.
Delphi mORMot PORN game
http://youtu.be/Jn6ODHkg6js

a) The game will require authentication; OK
b) the cards need to be shuffled, mormot should shuffle and deal hands; OK
c) on GameOver I need to "send scores" from SmartMS to my server and then immediately "show highscores TOP 5".

But something goes wrong here but I can't find out what.

When a player finishes a game just submit POST some data, the score to DB (NewRec) and then immediately I call another service to show highscores TOP 5 (GetRec). If the score is within a certain range at the top 5 and replay the game.

POST http://127.0.0.1:8080/root/Jogo.NewRec? … 9072891137
RESPONSE IS: 200
{"result":[56]}

POST http://127.0.0.1:8080/root/Jogo.GetRec? … 904733ef11
RESPONSE IS: 500

{
"errorCode":500,
"error":
{"ESQLite3Exception":{
    "ClassName":"ESQLite3Exception",
    "Address":"02EFFA7C",
    "ErrorCode": 5,
    "SQLite3ErrorCode": "BUSY",
    "Message": "Error SQLITE_BUSY (5) using 3.8.7.4 - \"database is locked\" extended_errcode=5"
}}
}

Any idea?

Last edited by warleyalex (2015-03-25 03:26:57)

ab

Administrator

From: France

Registered: 2010-06-21

Posts: 14,655

Website

Re: My mORMot game

First update your .obj files.
You are using an old version.

I guess you are opening the db file with an external tool: this is not possible since it locks the db.

warleyalex

Member

From: Sete Lagoas-MG, Brasil

Registered: 2013-01-20

Posts: 250

Re: My mORMot game

I think SQLite is supposed to be used for concurrent access using interface based services writing/reading in sequence. For me anyway, this is not working as expected. I suspect that some another process (NewRec?) has a lock on a database.  Maybe Props := TSQLDBSQLite3ConnectionProperties.Create(StringToUTF8('BasededadosSQLite.db3'),'','','');

I cannot reproduce the issue. f.i. In SmartMS, if i click in a button that fires NewRec/GetRec methods in sequence, server will throwing the 500 internal error. After some time (a basic DDOS attack), overthrow the server, server will crash.

// NewRec is an interface based service that adds "Name", "Moves" and "Time" to database.
     TServiceJogo.Create(Client).NewRec(20,20,
        lambda (res: integer)
          Result := res;
        end,
        lambda
          WriteLn('Error calling the method!');
        end);

// GetRec is an interface based service that return TOP 5,
SQL = 'SELECT Nome, Moves, Tempo FROM Game ORDER BY Moves,Tempo ASC LIMIT 5

     TServiceJogo.Create(Client).GetRec(
      lambda (res: variant)
        WriteLn(res);
      end,
      lambda
        WriteLn('Error calling the method!');
      end);

ab

Administrator

From: France

Registered: 2010-06-21

Posts: 14,655

Website

Re: My mORMot game

How do you use the DB?
Are you using an external SQLite3 database?
The whole SynSQLite3.pas access is protected by a critical section, so is thread safe, even when accessed from an external SQLite3 database.
So I do not know what it wrong in your case.

BTW why are you using raw SQL, and not the ORM?

warleyalex

Member

From: Sete Lagoas-MG, Brasil

Registered: 2013-01-20

Posts: 250

Re: My mORMot game

Thank you.
I'm just drunk enough to tell you that I'm re-using the same exact Sqlite3 file "BasededadosSQLite.db3" from both internal as well as external. Exactly, I have defined my server model, and DB and I use ORM to NewRec method.
TSQLRestServerDB.Create(Model, 'BasededadosSQLite.db3',true)  // method NewRec
Believe it or not, my "GetRec method" access sqlite as external database
TSQLDBSQLite3ConnectionProperties.Create('BasededadosSQLite.db3', '', '', '')

I think I can not switch from internal to external the way I'm doing to write and read sequencially. I suspect that some another process (NewRec?) will lock on a database in some moment. That way, my server overflows. I particularly like the end of the story, my mORMot server just went down.

ab

Administrator

From: France

Registered: 2010-06-21

Posts: 14,655

Website

Re: My mORMot game

The 'BasededadosSQLite.db3' DB is accessed twice!
Once from TSQLRestServerDB, and another time as external DB.
This is why it does not work.

You should just set a void in-memory DB for TSQLRestServerDB, then register all tables as external.