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vendor/github.com/avast/retry-go/retry.go

@@ -0,0 +1,206 @@
+/*
+Simple library for retry mechanism
+
+slightly inspired by [Try::Tiny::Retry](https://metacpan.org/pod/Try::Tiny::Retry)
+
+SYNOPSIS
+
+http get with retry:
+
+	url := "http://example.com"
+	var body []byte
+
+	err := retry.Do(
+		func() error {
+			resp, err := http.Get(url)
+			if err != nil {
+				return err
+			}
+			defer resp.Body.Close()
+			body, err = ioutil.ReadAll(resp.Body)
+			if err != nil {
+				return err
+			}
+
+			return nil
+		},
+	)
+
+	fmt.Println(body)
+
+[next examples](https://github.com/avast/retry-go/tree/master/examples)
+
+
+SEE ALSO
+
+* [giantswarm/retry-go](https://github.com/giantswarm/retry-go) - slightly complicated interface.
+
+* [sethgrid/pester](https://github.com/sethgrid/pester) - only http retry for http calls with retries and backoff
+
+* [cenkalti/backoff](https://github.com/cenkalti/backoff) - Go port of the exponential backoff algorithm from Google's HTTP Client Library for Java. Really complicated interface.
+
+* [rafaeljesus/retry-go](https://github.com/rafaeljesus/retry-go) - looks good, slightly similar as this package, don't have 'simple' `Retry` method
+
+* [matryer/try](https://github.com/matryer/try) - very popular package, nonintuitive interface (for me)
+
+BREAKING CHANGES
+
+1.0.2 -> 2.0.0
+
+* argument of `retry.Delay` is final delay (no multiplication by `retry.Units` anymore)
+
+* function `retry.Units` are removed
+
+* [more about this breaking change](https://github.com/avast/retry-go/issues/7)
+
+
+0.3.0 -> 1.0.0
+
+* `retry.Retry` function are changed to `retry.Do` function
+
+* `retry.RetryCustom` (OnRetry) and `retry.RetryCustomWithOpts` functions are now implement via functions produces Options (aka `retry.OnRetry`)
+
+
+*/
+package retry
+
+import (
+	"fmt"
+	"strings"
+	"time"
+)
+
+// Function signature of retryable function
+type RetryableFunc func() error
+
+var (
+	DefaultAttempts      = uint(10)
+	DefaultDelay         = 100 * time.Millisecond
+	DefaultMaxJitter     = 100 * time.Millisecond
+	DefaultOnRetry       = func(n uint, err error) {}
+	DefaultRetryIf       = IsRecoverable
+	DefaultDelayType     = CombineDelay(BackOffDelay, RandomDelay)
+	DefaultLastErrorOnly = false
+)
+
+func Do(retryableFunc RetryableFunc, opts ...Option) error {
+	var n uint
+
+	//default
+	config := &Config{
+		attempts:      DefaultAttempts,
+		delay:         DefaultDelay,
+		maxJitter:     DefaultMaxJitter,
+		onRetry:       DefaultOnRetry,
+		retryIf:       DefaultRetryIf,
+		delayType:     DefaultDelayType,
+		lastErrorOnly: DefaultLastErrorOnly,
+	}
+
+	//apply opts
+	for _, opt := range opts {
+		opt(config)
+	}
+
+	var errorLog Error
+	if !config.lastErrorOnly {
+		errorLog = make(Error, config.attempts)
+	} else {
+		errorLog = make(Error, 1)
+	}
+
+	lastErrIndex := n
+	for n < config.attempts {
+		err := retryableFunc()
+
+		if err != nil {
+			errorLog[lastErrIndex] = unpackUnrecoverable(err)
+
+			if !config.retryIf(err) {
+				break
+			}
+
+			config.onRetry(n, err)
+
+			// if this is last attempt - don't wait
+			if n == config.attempts-1 {
+				break
+			}
+
+			delayTime := config.delayType(n, config)
+			if config.maxDelay > 0 && delayTime > config.maxDelay {
+				delayTime = config.maxDelay
+			}
+			time.Sleep(delayTime)
+		} else {
+			return nil
+		}
+
+		n++
+		if !config.lastErrorOnly {
+			lastErrIndex = n
+		}
+	}
+
+	if config.lastErrorOnly {
+		return errorLog[lastErrIndex]
+	}
+	return errorLog
+}
+
+// Error type represents list of errors in retry
+type Error []error
+
+// Error method return string representation of Error
+// It is an implementation of error interface
+func (e Error) Error() string {
+	logWithNumber := make([]string, lenWithoutNil(e))
+	for i, l := range e {
+		if l != nil {
+			logWithNumber[i] = fmt.Sprintf("#%d: %s", i+1, l.Error())
+		}
+	}
+
+	return fmt.Sprintf("All attempts fail:\n%s", strings.Join(logWithNumber, "\n"))
+}
+
+func lenWithoutNil(e Error) (count int) {
+	for _, v := range e {
+		if v != nil {
+			count++
+		}
+	}
+
+	return
+}
+
+// WrappedErrors returns the list of errors that this Error is wrapping.
+// It is an implementation of the `errwrap.Wrapper` interface
+// in package [errwrap](https://github.com/hashicorp/errwrap) so that
+// `retry.Error` can be used with that library.
+func (e Error) WrappedErrors() []error {
+	return e
+}
+
+type unrecoverableError struct {
+	error
+}
+
+// Unrecoverable wraps an error in `unrecoverableError` struct
+func Unrecoverable(err error) error {
+	return unrecoverableError{err}
+}
+
+// IsRecoverable checks if error is an instance of `unrecoverableError`
+func IsRecoverable(err error) bool {
+	_, isUnrecoverable := err.(unrecoverableError)
+	return !isUnrecoverable
+}
+
+func unpackUnrecoverable(err error) error {
+	if unrecoverable, isUnrecoverable := err.(unrecoverableError); isUnrecoverable {
+		return unrecoverable.error
+	}
+
+	return err
+}