如何处理来自 socket.io 房间“发射”事件的多个写入函数？

Question

Going to provide some context first. Question is at the bottom.

Background

I'm making a browser based javascript game where users join a room and move tiles around. When the game is over, user data is sent to the server, where it needs to be merged with other user data, and then the resulting data gets sent back to each user to display the results of other players.

I am using an Express node server with socket.io (front end is react, fwiw)

The issue at hand

I have a json file for a game room, lets call it 1a2b.json :

{
  "roomID":"1a2b",
  "users":[
    {
      "name":"username",
      "id": 123,
      "tiles":[
        {"char":"I","x":false,"y":false,"r":false,"id":"1"},
        {"char":"X","x":false,"y":false,"r":false,"id":"2"}
      ]
    }
    {
      "name":"username2",
      "id": 456,
      "tiles":[
        {"char":"V","x":false,"y":false,"r":false,"id":"3"},
        {"char":"K","x":false,"y":false,"r":false,"id":"4"}
      ]
    }
  ]
}

When a game ends, players emit a socket event ( game-end ) that sends updated player tiles data. Something like:

{
  "name":"username",
  "id": 123,
  "roomID":"1a2b",
  "tiles":[
    {"char":"I","x":21,"y":30,"r":"45deg","id":"1"},
    {"char":"X","x":50,"y":80,"r":false,"id":"2"}
  ]
}

On the server, when the game-end socket event is observed, I need to update the original 1a2b.json file with the new data from each user, replacing the old tiles data for a player with the new tiles data.

All users will be emitting the event at the same time, which I assume will cause an fs.writefile error for some users.

The Question

How do I handle updating and writing the contents of 1a2b.json when multiple update/write events are happening at the same time to the same file? And within a proposed solution, is there a way to tell when all write requests are complete, so I can emit data from the completed json file back to users?

Answer 1

If you're just running one Express instance, since Node is single-threaded, the server will only be able to process one write at a time anyway. So you will not encounter any errors.

The real solution would be to write to a database rather than a file.