Go Context Timeout Example

This example demonstrates how to use Go's context package to handle timeouts in HTTP requests.

Flow Diagram

sequenceDiagram
    participant Client
    participant Main
    participant simulateSlowRequest
    participant fetchTodo
    participant API
    
    Client->>Main: Start program
    Main->>Main: Create context with 2s timeout
    Main->>simulateSlowRequest: Call with todoID=1, minDuration=3s
    
    Note over simulateSlowRequest: Goroutine starts
    
    simulateSlowRequest->>simulateSlowRequest: Sleep for 3s
    
    alt Context times out (2s elapsed)
        Main->>simulateSlowRequest: Context Done
        simulateSlowRequest-->>Main: Return timeout error
        Main-->>Client: "Error: request timed out..."
    else Request completes (before timeout)
        simulateSlowRequest->>fetchTodo: Make HTTP request
        fetchTodo->>API: GET /todos/1
        API-->>fetchTodo: Return todo data
        fetchTodo-->>simulateSlowRequest: Return todo
        simulateSlowRequest-->>Main: Return todo
        Main-->>Client: "Successfully fetched todo..."
    end

Loading

How It Works

1. The program creates a context with a 2-second timeout
2. It calls simulateSlowRequest with a minimum duration of 3 seconds
3. The request is designed to take longer than the context timeout
4. The context cancels the operation after 2 seconds
5. The program handles the timeout gracefully

Running the Example

go run main.go

Expected Output

When the request times out:

2023/10/07 12:25:00 Fetching todo with ID 1...
2023/10/07 12:25:02 Error: request timed out after 3s: context deadline exceeded
2023/10/07 12:25:02 This demonstrates how context timeout prevents waiting too long for a response.

When the request succeeds (if you reduce the minDuration to less than 2s):

2023/10/07 12:30:00 Fetching todo with ID 1...
2023/10/07 12:30:01 Successfully fetched todo: &{UserID:1 ID:1 Title:delectus aut autem Completed:false}

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the MIT License - see the LICENSE file for details.