re.Try Function

re.Try provides a simple and idiomatic way to implement retry logic in Go. It executes a function repeatedly until it succeeds or a timeout occurs.

Import

go get github.com/digitalstraw/retry-go/re

Usage

The function accepts two parameters:

• fn: A function that returns a value of type T and an error.
• rp: An optional implementation of the re.TryPolicy interface defining the retry behavior.

Default Usage

If no retry policy is specified, re.Const() is used by default, with a 30-second timeout and a 1-second interval between attempts.

db, err := re.Try(ctx, func() (*sql.DB, error) {
    return sql.Open("mysql", dsn)
})

Using the Default Backoff Retry Policy

The Backoff policy in its default configuration has a 2-minute timeout with a doubling interval between attempts, starting at 100ms.

fn := func() (*sql.DB, error) {
    return sql.Open("mysql", dsn)
}
db, err := re.Try(ctx, fn, re.Backoff())

Fully Customized Backoff Retry Policy

fn := func() (*sql.DB, error) {
    return sql.Open("mysql", dsn)
}
// Genrates the following sleep durations: 100ms, 300ms, 900ms, 2.7s, 8.1s, 24.3s, 60s, 60s, ...
db, err := re.Try(ctx, fn, re.Backoff().WithFactor(3).WithInterval(100*time.Millisecond).WithMaxInterval(60*time.Second).WithTimeout(5*time.Minute))

Custom Retry Policies

You can define your own retry policies by implementing the re.TryPolicy interface.

Example: Custom Policy

const (
	defaultTimeout = 10 * time.Second
)

type CustomPolicy struct {
	*re.Policy

	failures int
}

var _ re.TryPolicy = (*CustomPolicy)(nil)

func Custom() *CustomPolicy {
	c := &CustomPolicy{}
	c.Policy = &re.Policy{
		Interval: 1 * time.Second,
		StopAt:   time.Now().Add(defaultTimeout),
		Self:     c,
	}
	return c
}

// SleepDuration produces following durations in default: 3s, 5s, 7s, timeout.
func (c *CustomPolicy) SleepDuration(attempt int, _ time.Duration) time.Duration {
	c.failures++
	return c.Interval + time.Duration(attempt)*2*time.Second // Custom logic
}

func (c *CustomPolicy) Failures() int {
	return c.failures
}

Using Custom Policy

fn := func() (*sql.DB, error) {
    return sql.Open("mysql", dsn)
}
db, err := re.Try(ctx, fn, Custom().WithTimeout(1*time.Minute))

How to Run Linter

To run the linter, use the following command in the terminal:

golangci-lint run --fix --build-tags=tests

Contributing

Contributions are welcome! Please open an issue or submit a pull request on GitHub.

License

This code is licensed under the MIT License. See the LICENSE file for details.

Changelog

• v1.0.0

  • Added context parameter to Try() function.
  • Immediate reaction to context cancellation implemented.
  • re.Sleep(ctx, duration) function added to support context-aware sleeping.
  • Improved processing when timeout is reached:
    • We run fn one last time before the timeout.
    • This ensures the final sleep period isn't wasted, especially in Backoff scenarios where that last wait could be long.

• v0.0.1

  • Initial release with basic retry functionality and default policies.