balancers.CreateFromConfig + balancer.Balancer.Create

Author: asmyasnikov

CHANGELOG.md

@@ -1,5 +1,9 @@
+## 3.14.1
+* Added `balacers.CreateFromConfig` balancer creator
+* Added `Create` method to interface `balancer.Balancer`
+
 ## 3.14.0
-* Added `balacers.FromConfig` balancers creator
+* Added `balacers.FromConfig` balancer creator
 
 ## 3.13.3
 * Fixed linter issues

balancers/config.go

@@ -48,23 +48,15 @@ func WithParseErrorHandler(errorHandler func(error)) fromConfigOption {
 	}
 }
 
-func FromConfig(config string, opts ...fromConfigOption) (b balancer.Balancer) {
+func CreateFromConfig(config string) (balancer.Balancer, error) {
 	var (
-		h = fromConfigOptionsHolder{
-			fallbackBalancer: Default(),
-		}
-		c balancersConfig
+		b   balancer.Balancer
+		err error
+		c   balancersConfig
 	)
 
-	for _, o := range opts {
-		o(&h)
-	}
-
-	if err := json.Unmarshal([]byte(config), &c); err != nil {
-		if h.errorHandler != nil {
-			h.errorHandler(err)
-		}
-		return h.fallbackBalancer
+	if err = json.Unmarshal([]byte(config), &c); err != nil {
+		return nil, err
 	}
 
 	switch c.Type {
@@ -75,30 +67,47 @@ func FromConfig(config string, opts ...fromConfigOption) (b balancer.Balancer) {
 	case typeRoundRobin:
 		b = RoundRobin()
 	default:
-		if h.errorHandler != nil {
-			h.errorHandler(errors.Errorf("unknown type of balancer: %s", c.Type))
-		}
-		return h.fallbackBalancer
+		return nil, errors.Errorf("unknown type of balancer: %s", c.Type)
 	}
 
 	switch c.Prefer {
 	case preferLocalDC:
 		if c.Fallback {
-			return PreferLocalDCWithFallBack(b)
+			return PreferLocalDCWithFallBack(b), nil
 		}
-		return PreferLocalDC(b)
+		return PreferLocalDC(b), nil
 	case preferLocations:
 		if len(c.Locations) == 0 {
-			if h.errorHandler != nil {
-				h.errorHandler(errors.Errorf("empty locations list in balancer '%s' config", c.Type))
-			}
-			return h.fallbackBalancer
+			return nil, errors.Errorf("empty locations list in balancer '%s' config", c.Type)
 		}
 		if c.Fallback {
-			return PreferLocationsWithFallback(b, c.Locations...)
+			return PreferLocationsWithFallback(b, c.Locations...), nil
 		}
-		return PreferLocations(b, c.Locations...)
+		return PreferLocations(b, c.Locations...), nil
 	default:
-		return b
+		return b, nil
 	}
 }
+
+func FromConfig(config string, opts ...fromConfigOption) balancer.Balancer {
+	var (
+		h = fromConfigOptionsHolder{
+			fallbackBalancer: Default(),
+		}
+		b   balancer.Balancer
+		err error
+	)
+	for _, o := range opts {
+		o(&h)
+	}
+
+	b, err = CreateFromConfig(config)
+	if err != nil {
+		if h.errorHandler != nil {
+			h.errorHandler(err)
+		}
+		return h.fallbackBalancer
+	}
+
+	return b
+}

balancers/config_test.go

@@ -10,6 +10,10 @@ import (
 
 type testBalancer struct{}
 
+func (t testBalancer) Create() balancer.Balancer {
+	panic("unexpected call")
+}
+
 func (t testBalancer) Next() conn.Conn {
 	panic("unexpected call")
 }

internal/balancer/balancer.go

@@ -29,8 +29,7 @@ type Balancer interface {
 
 	// Contains returns true if Balancer contains requested element.
 	Contains(Element) bool
-}
 
-type Creator interface {
+	// Create makes empty balancer with same implementation
 	Create() Balancer
 }

internal/balancer/multi/multi.go

@@ -26,7 +26,7 @@ type multi struct {
 func (m *multi) Create() balancer.Balancer {
 	bb := make([]balancer.Balancer, len(m.balancer))
 	for i, b := range m.balancer {
-		bb[i] = b.(balancer.Creator).Create()
+		bb[i] = b.Create()
 	}
 	return &multi{
 		balancer: bb,

internal/balancer/stub/stub.go

@@ -16,6 +16,7 @@ type stubBalancer struct {
 	OnRemove    func(balancer.Element) bool
 	OnPessimize func(context.Context, balancer.Element) error
 	OnContains  func(balancer.Element) bool
+	OnCreate    func() balancer.Balancer
 }
 
 func Balancer() (*list.List, balancer.Balancer) {
@@ -55,6 +56,13 @@ func Balancer() (*list.List, balancer.Balancer) {
 	}
 }
 
+func (s stubBalancer) Create() balancer.Balancer {
+	if f := s.OnCreate; f != nil {
+		return f()
+	}
+	return nil
+}
+
 func (s stubBalancer) Next() conn.Conn {
 	if f := s.OnNext; f != nil {
 		return f()

internal/meta/version.go

@@ -1,5 +1,5 @@
 package meta
 
 const (
-	Version = "ydb-go-sdk/3.14.0"
+	Version = "ydb-go-sdk/3.14.1"
 )

with.go

@@ -3,8 +3,6 @@ package ydb
 import (
 	"context"
 	"sync/atomic"
-
-	"github.com/ydb-platform/ydb-go-sdk/v3/internal/balancer"
 )
 
 var nextID = uint64(0)
@@ -14,14 +12,12 @@ func (c *connection) With(ctx context.Context, opts ...Option) (Connection, erro
 		return c, nil
 	}
 
-	if creator, ok := c.config.Balancer().(balancer.Creator); ok {
-		opts = append(
-			opts,
-			WithBalancer(
-				creator.Create(),
-			),
-		)
-	}
+	opts = append(
+		opts,
+		WithBalancer(
+			c.config.Balancer().Create(),
+		),
+	)
 
 	id := atomic.AddUint64(&nextID, 1)