MM-28859 Add feature flag managment system using split.io and remove viper. (#15954)

* Add feature flag managment system using split.io and remove viper.

* Fixing tests.

* Attempt to fix postgres tests.

* Fix watch filepath for advanced logging.

* Review fixes.

* Some error wrapping.

* Remove unessisary store interface.

* Desanitize SplitKey

* Simplify.

* Review feedback.

* Rename split mlog adatper to split logger.

* fsInner

* Style.

* Restore oldcfg test.

* Downgrading non-actionable feature flag errors to warnings.

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

vendor/github.com/splitio/go-toolkit/v3/common/iterutil.go

@@ -0,0 +1,67 @@
+package common
+
+import (
+	"errors"
+	"math"
+	"time"
+)
+
+// WithAttempts executes a function N times or until no error is returned
+func WithAttempts(attempts int, main func() error) error {
+	err := errors.New("")
+	remaining := attempts
+	for err != nil && remaining > 0 {
+		remaining--
+		err = main()
+	}
+	return err
+}
+
+// WithBackoff wraps the function to add Exponential backoff
+func WithBackoff(duration time.Duration, main func() error) func() error {
+	var count time.Duration = 1
+	return func() error {
+		err := main()
+		if err != nil {
+			time.Sleep(count * duration)
+			count++
+		} else {
+			count = 0
+		}
+		return main()
+	}
+}
+
+// WithBackoffCancelling wraps the function to add Exponential backoff
+func WithBackoffCancelling(unit time.Duration, max time.Duration, main func() bool) func() {
+	cancel := make(chan struct{})
+	go func() {
+		attempts := 0
+		isDone := main()
+
+		// Create timeout timer for backoff
+		backoffTimer := time.NewTimer(MinDuration(time.Duration(math.Pow(2, float64(attempts)))*unit, max))
+		defer backoffTimer.Stop()
+
+		for !isDone {
+			attempts++
+
+			// Setting timer considerint attempts
+			backoffTimer.Reset(MinDuration(time.Duration(math.Pow(2, float64(attempts)))*unit, max))
+
+			select {
+			case <-cancel:
+				return
+			case <-backoffTimer.C: // Timedout
+				isDone = main()
+			}
+		}
+	}()
+	return func() {
+		select {
+		case cancel <- struct{}{}:
+			return
+		default:
+		}
+	}
+}

vendor/github.com/splitio/go-toolkit/v3/common/refutil.go

@@ -0,0 +1,105 @@
+package common
+
+// StringRef returns ref
+func StringRef(str string) *string {
+	return &str
+}
+
+// IntRef returns ref
+func IntRef(number int) *int {
+	return &number
+}
+
+// Int64Ref returns ref
+func Int64Ref(number int64) *int64 {
+	return &number
+}
+
+// Float64Ref returns ref
+func Float64Ref(number float64) *float64 {
+	return &number
+}
+
+// Int64Value returns value
+func Int64Value(number *int64) int64 {
+	if number == nil {
+		return 0
+	}
+	return *number
+}
+
+// IntRefOrNil returns ref
+func IntRefOrNil(number int) *int {
+	if number == 0 {
+		return nil
+	}
+	return IntRef(number)
+}
+
+// Int64RefOrNil returns ref
+func Int64RefOrNil(number int64) *int64 {
+	if number == 0 {
+		return nil
+	}
+	return Int64Ref(number)
+}
+
+// StringRefOrNil returns ref
+func StringRefOrNil(str string) *string {
+	if str == "" {
+		return nil
+	}
+	return StringRef(str)
+}
+
+// AsIntOrNil returns ref
+func AsIntOrNil(data interface{}) *int {
+	if data == nil {
+		return nil
+	}
+
+	number, ok := data.(int)
+	if !ok {
+		return nil
+	}
+	return IntRef(number)
+}
+
+// AsInt64OrNil returns ref
+func AsInt64OrNil(data interface{}) *int64 {
+	if data == nil {
+		return nil
+	}
+
+	number, ok := data.(int64)
+	if !ok {
+		return nil
+	}
+	return Int64Ref(number)
+}
+
+// AsFloat64OrNil return ref
+func AsFloat64OrNil(data interface{}) *float64 {
+	if data == nil {
+		return nil
+	}
+
+	number, ok := data.(float64)
+	if !ok {
+		return nil
+	}
+	return Float64Ref(number)
+}
+
+// AsStringOrNil returns ref
+func AsStringOrNil(data interface{}) *string {
+	if data == nil {
+		return nil
+	}
+
+	str, ok := data.(string)
+	if !ok {
+		return nil
+	}
+	return StringRef(str)
+}

vendor/github.com/splitio/go-toolkit/v3/common/sliceutil.go

@@ -0,0 +1,18 @@
+package common
+
+// Partition create partitions considering the passed amount
+func Partition(items []string, maxItems int) [][]string {
+	var splitted [][]string
+
+	for i := 0; i < len(items); i += maxItems {
+		end := i + maxItems
+
+		if end > len(items) {
+			end = len(items)
+		}
+
+		splitted = append(splitted, items[i:end])
+	}
+
+	return splitted
+}

vendor/github.com/splitio/go-toolkit/v3/common/strutil.go

@@ -0,0 +1,9 @@
+package common
+
+// StringValueOrDefault returns original value if not empty. Default otherwise.
+func StringValueOrDefault(str string, def string) string {
+	if str != "" {
+		return str
+	}
+	return def
+}

vendor/github.com/splitio/go-toolkit/v3/common/timeutil.go

@@ -0,0 +1,25 @@
+package common
+
+import "time"
+
+// MinDuration returns the min duration among them
+func MinDuration(d1, d2 time.Duration, ds ...time.Duration) time.Duration {
+	min := d1
+	for _, d := range append(ds, d2) {
+		if d < min {
+			min = d
+		}
+	}
+	return min
+}
+
+// MaxDuration returns the max duration among them
+func MaxDuration(d1, d2 time.Duration, ds ...time.Duration) time.Duration {
+	max := d1
+	for _, d := range append(ds, d2) {
+		if d > max {
+			max = d
+		}
+	}
+	return max
+}