How is the recovery function in golang function implemented?

The recover function in the Go language is implemented through the scheduler to manage the panic record in the goroutine, which is used to capture and handle unexpected errors. It only captures the panic in the current goroutine, and uses the defer statement to execute the recovery function before the function returns. The recovery function receives the panic value of interface{} type and prints a more friendly error message.

How the recovery function in Go function is implemented

The recover function in Go language allows Recover panics from running goroutines. It is very useful in catching and handling unexpected errors.

Implementation

recover The implementation is based on the Go language scheduler. The scheduler is responsible for managing the execution of goroutines. It maintains a panic record, which stores the latest panic value.

When a panic occurs, the scheduler saves the panic value in the panic record and terminates the currently executing goroutine. It then hands control to the runtime which marks the goroutine as "dead".

If other goroutines are waiting for this goroutine to exit, they will receive a Recover message. The message contains the panic value from the panic record.

Practical case

Suppose we have a function that may cause panic:

func DivideByZero(x, y int) {
    if y == 0 {
        panic("division by zero")
    }
    fmt.Println(x / y)
}

We can use recover to recover from panic Recover, and print a friendlier error message:

func main() {
    defer func() {
        if err := recover(); err != nil {
            fmt.Println("Error:", err)
        }
    }()

    DivideByZero(10, 0)
}

Output:

Error: division by zero

Note

• defer statement is used to run the recovery function before the function returns.
• The recovery function is an anonymous function that requires a interface{} type parameter to receive the panic value.
• The recovery function only captures panics in the current goroutine. It cannot catch panics in other goroutines.

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