retry

Golang retry library.

About The Project

Retry - small library, that provides api for easy function retry and error handling. Package has some benefits unlike known implementations:

laconic api
rich retry strategy set
easy customization
context package support

Usage

Retry function until success:

_ = retry.Exec(func(retryNumber int) (err error) {
    // your logic here
    return err
})

Limit attempts:

err := retry.Exec(func(retryNumber int) (err error) {
    // your logic here
    return err
}, retry.MaxAttempts(10))

Delay between retries:

err := retry.Exec(func(retryNumber int) (err error) {
    // your logic here
    return err
}, retry.FixedDelay(time.Second))

Combine few retry strategies:

err := retry.Exec(func(retryNumber int) (err error) {
    // your logic here
    return err
}, retry.MaxAttempts(10), retry.FixedDelay(time.Second))

Breaking retry loop directly from function:

err := retry.Exec(func(retryNumber int) (err error) {
    // your logic here
    if !canRetry {
        return retry.Unrecoverable(err)
    }
    return err
})

Using context:

err := retry.ExecContext(ctx, func(ctx context.Context, retryNumber int) (err error) {
    // your logic here
    return err
})

Context cancellation:

ctx, cancel := context.WithCancel(context.Background())
go func() {
    // wait some event
    cancel()
}()
err := retry.ExecContext(ctx, func(ctx context.Context, retryNumber int) (err error) {
    // your logic here
    return err
})

Underwater rocks

Arguments order

Be careful:

err := retry.Exec(func(retryNumber int) (err error) {
    // your logic here
    return err
}, retry.MaxAttempts(2), retry.FixedDelay(time.Second))

not similar to

err := retry.Exec(func(retryNumber int) (err error) {
    // your logic here
    return err
}, retry.FixedDelay(time.Second), retry.MaxAttempts(2))

Trace steps in the first case are:

Function call
Max attempts check
Delay
Function call
Max attempts check
Break loop

Trace steps in the second case are:

Function call
Delay
Max attempts check
Function call
Delay
Max attempts check
Break loop

So, we can see, that second block of code will have unnecessary delay. It is highly recommended to store strategies, that limit attempts, before strategies, that do delays.

Strategy reusing

Some strategies have internal state, so it is highly recommended not to share strategies between several Exec calls.

Incorrect:

strategy := retry.MaxAttempts(2)
err := retry.Exec(func(retryNumber int) (err error) {
    // your logic here
    return err
}, strategy)
err := retry.Exec(func(retryNumber int) (err error) {
    // your logic here
    return err
}, strategy)

Correct:

err := retry.Exec(func(retryNumber int) (err error) {
    // your logic here
    return err
}, retry.MaxAttempts(2))
err := retry.Exec(func(retryNumber int) (err error) {
    // your logic here
    return err
}, retry.MaxAttempts(2))

Similar projects

License

Retry is licensed under the Apache License, Version 2.0. See LICENSE for the full license text.

Contact

Email: cherkashin.evgeny.viktorovich@gmail.com
Telegram: @evgeny_cherkashin

CherkashinEvgeny / goretry