4 ms·

> This is because node is nonblocking. It doesn't wait for get_username() to return before continuing. You misunderstand how non-blocking works. In this case,

by aGHz 14y ago

> This is because node is nonblocking. It doesn't wait for get_username() to return before continuing. You misunderstand how non-blocking works. In this case, it -most definitely- waits for get_username() to return before continuing. If get_username itself does some asynchronous calls (like db.query), that's its problem, but execution absolutely waits for your own functions to finish. I'd recommend reading up more on event-driven programming.

blhack 14y ago
Great, could you point me somewhere to learn more about the topic?
- aGHz 14y ago
  Sorry, nothing off the top of my head, but a good starting point would be googling for stuff like "node event driven" or maybe "event driven programming" in general.
  - blhack 14y ago
    Not sure if you're still monitoring this thread [no HN notifications, eh?], but here's my question: My get_username() function, say I have this code: var server = http.createServer(function(req, res) { username = get_username(); res.writeHead(200); res.write("<html>"); res.write("You are " + username); res.end("bye"); This obviously won't work, res.end() gets fired long before my DB query in get_username() finishes. How else would I accomplish what I'm trying to do here other than putting my response stuff in the DB query's callback function? <Sorry for the newb question, buy what I'm doing: having the response generated inside of the query's callback, seems to be the way most of these node tutorials suggest.>
    - aGHz 14y ago
      Manually, you could structure it in several functions like prepare_response() and render_response(), possibly with other functions in-between for the various chunks of data you need in your response. When all the chunks are ready, you finally call render_response() and send it. In practice, you can find a ton of libraries that can help you manage this [1], I -believe- the most recommended one would be 'futures'. [1] https://github.com/joyent/node/wiki/modules#wiki-async-flow https://github.com/joyent/node/wiki/modules#wiki-async-flow

by aGHz 14y ago

blhack 14y ago

Great, could you point me somewhere to learn more about the topic?

aGHz 14y ago
Sorry, nothing off the top of my head, but a good starting point would be googling for stuff like "node event driven" or maybe "event driven programming" in general.
- blhack 14y ago
  Not sure if you're still monitoring this thread [no HN notifications, eh?], but here's my question: My get_username() function, say I have this code: var server = http.createServer(function(req, res) { username = get_username(); res.writeHead(200); res.write("<html>"); res.write("You are " + username); res.end("bye"); This obviously won't work, res.end() gets fired long before my DB query in get_username() finishes. How else would I accomplish what I'm trying to do here other than putting my response stuff in the DB query's callback function? <Sorry for the newb question, buy what I'm doing: having the response generated inside of the query's callback, seems to be the way most of these node tutorials suggest.>
  - aGHz 14y ago
    Manually, you could structure it in several functions like prepare_response() and render_response(), possibly with other functions in-between for the various chunks of data you need in your response. When all the chunks are ready, you finally call render_response() and send it. In practice, you can find a ton of libraries that can help you manage this [1], I -believe- the most recommended one would be 'futures'. [1] https://github.com/joyent/node/wiki/modules#wiki-async-flow https://github.com/joyent/node/wiki/modules#wiki-async-flow