Database sessions for web applications

[jaybill]

So I'm building a web application that uses mgo. When the app starts, I create a database session and cram a pointer to it in a "context" struct. I then pass a pointer to the context struct (which has other things in it, like the configuration data I loaded from a file, etc.) into my handlers. My logic here was that I didn't want to make a new db connection on every request.

This works, but I'm not sure if it's a good idea. The db session never gets closed and stays open (I presume) until I kill the app. (Calling close with "defer" closes the session before I get to use it.)

Is this the right strategy? If not, where's the right place to make database connections?

Thanks in advance!

[Gustavo Niemeyer]

Hey there,

It's fine to pick a new session whenever you please (session.Copy, for
example), and closing it when the logic is done with whatever was
being done (maybe handling a request). This will internally put the
connection used back into the pool for reuse on the next session.

If you're using only the base session rather than copying it, that's
fine as well for most applications where concurrency isn't necessary.
In those cases you can session.Refresh() at the end of the procedure
rather than session.Close(), so that the connection is put back into
the pool.

--
Gustavo Niemeyer
http://niemeyer.net
http://niemeyer.net/plus
http://niemeyer.net/twitter
http://niemeyer.net/blog

-- I'm not absolutely sure of anything.

[jaybill]

Thanks so much for the quick reply! That answers my question perfectly!

--Jaybill

On Wednesday, April 11, 2012 3:16:14 PM UTC-7, Gustavo Niemeyer wrote:

Hey there,

[nvcnvn]

Forgive for my stupid, but...how do I copy the session?

Can some one give me an example with my code here:

_______________________________

type Hello struct {

session *mgo.Session

}

func (h Hello) ServeHTTP(w http.ResponseWriter, r *http.Request) {

fmt.Fprint(w, "Hello!")

//Get some data from mongo here

}

func main() {

var h Hello

http.ListenAndServe("localhost:4000",h)

}

_______________________________

Thanks you!
Vào 05:16:14 UTC+7 Thứ năm, ngày 12 tháng tư năm 2012, Gustavo Niemeyer đã viết:

[nvcnvn]

Is my code right:

_________________________________________________________

type Hello struct {

session *mgo.Session

}

func (h Hello) ServeHTTP(w http.ResponseWriter, r *http.Request) {

s := h.session.Copy()

}

func main() {

var h Hello

h.session, err := mgo.Dial("server1.example.com,server2.example.com")

if err != nil { panic(err) }

http.ListenAndServe("localhost:4000",h)

}

__________________________________________________________

Vào 05:16:14 UTC+7 Thứ năm, ngày 12 tháng tư năm 2012, Gustavo Niemeyer đã viết:

Hey there,

[Gustavo Niemeyer]

Heya,

> Is my code right:
(...)

> func (h Hello) ServeHTTP(w http.ResponseWriter, r *http.Request) {
> s := h.session.Copy()

Almost. You can either use h.session directly here, if you're happy
with a single connection to the database, or you have to call:

defer s.Close()

here, to avoid having this copied session leaking.