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WithDeadline function in context package in Go

Here, we will are going to learn about WithDeadline function in context package in Go with example in details.

The ‘WithDeadline’ function is a part of the context package that returns a derived context and a cancellation function. The derived context is a copy of the parent context with an additional deadline property. When the deadline is reached, the derived context is automatically canceled. This can be useful when you need to enforce a timeout on a long-running process or when you need to propagate a deadline through a chain of function calls.

Syntax:

func WithDeadline(parent Context, d time.Time) (Context, CancelFunc)

Example:

Let’s create a simple example to demonstrate the use of the ‘WithDeadline’ function. We will create a small Go application that simulates a long-running process and shows how to use the ‘WithDeadline’ function to enforce a deadline on the process.

package main


import (

	"context"

	"fmt"

	"time"

)


func longRunningProcess(ctx context.Context) {

	for {

		select {

		case <-ctx.Done():

			fmt.Println("Process stopped")

			return

		default:

			fmt.Println("Process running...")

			time.Sleep(1 * time.Second)

		}

	}

}


func main() {

	parentCtx := context.Background()

	deadline := time.Now().Add(5 * time.Second)

	ctx, cancel := context.WithDeadline(parentCtx, deadline)

	defer cancel()


	go longRunningProcess(ctx)


	time.Sleep(7 * time.Second)

	fmt.Println("Main function completed")

}


In this example, the longRunningProcess function simulates a long-running process by repeatedly printing “Process running…” every second. It uses the context’s Done channel to listen for a cancellation signal. If a cancellation signal is received, it prints “Process stopped” and returns, effectively stopping the process.

In the main function, we create a parent context using context.Background() and then create a derived context and a cancellation function using the ‘WithDeadline’ function. We set a deadline of 5 seconds from the current time. We start the long-running process in a separate goroutine, passing the derived context to it. The main function waits for 7 seconds before completing, giving the long-running process time to detect the deadline and terminate.

Output:

Process running...
Process running...
Process running...
Process running...
Process stopped
Main function completed

To learn more about golang, Please refer given below link.

https://www.techieindoor.com/context-package-in-go/

References:

https://golang.org/doc/

Posted in context, golang, packages

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