I use semi-code here just to show my intention of whats going on in code and not complicating things here in the question.
I have a main.go file that calls a method that connects to mongoDB database:
mStore := store.NewMongoStore()
In NewMongoStore I have context that client.Connect uses to connect to database:
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
Now in main.go I pass the store to my router controller file this way:
routes.GenericRoute(router, mStore)
In GenericRoute I get the mStore and pass it to function handlers:
func GenericRoute(router *gin.Engine, mStore store.Store) {
router.POST("/users", controllers.CreateUser(mStore))
}
Now in CreateUser I again create a context as below to insert document into MongoDB:
ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
defer cancel()
insertedId, err := repo.CreateUser(ctx, newUser{"John", "Doe"})
Here I passed context to createUser to insert a new document.
As you see in some parts I have passed context and in some parts I did not. I really do not have any idea what I should do? What is the correct way to work with contexts? Should I always pass context around or it is totally ok to create new contexts like this to not pass context in method parameters.
What is the best practice for this kind of coding? And which one is better from performance point of view?
I reached to an interesting answer to my own question, so I prefer to put here for future users if having the same question in mind.
If I pass the SAME context that I have connected to Mongo with to userController and pass it down further to CreateUser function:
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
NOTE: instead of cancelling context in NewMongoStore function I defer cancel() it in main function.
After 10 seconds if you call POST /users you will get context deadline exceeded, so basically you cannot use this context to do other stuff and you have to create new context on each CreateUser call.
So what I have written is fine. I wait for 10 seconds to connect to mongo in my example and 1 second for my insert operation context.