Context Package

• We need a way to propagate request-scoped data down the call graph.
• We need a way to propagate cancellation signal down the call graph.
• Across API bundaries to all goroutines involved in handling a request.

Context package serves two primary purpos

1. Provides API's for cancelling branches of call graph.
2. Provides a data-bag for transporting request-scoped data through call graph.

Context package provides functions to create new context

• context.Background()
• context.TODO()

context.Background()

func main(){
    ctx := context.Background()
}

• Background return an empty context.
• Root of any context tree.
• It is never canceled, has no value and has no deadline.
• Acts as a top level context for incoming request.

context.TODO()

func main(){
    ctx := context.TODO()
}

• TODO() return an empty context.
• TODO's intended purpose is to serve as a placeholder.