[#74] Add round tree retry

Signed-off-by: Denis Kirillov <d.kirillov@yadro.com>

internal/frostfs/services/tree_client_grpc.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"strings"
+	"sync/atomic"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api"
 	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/data"
@@ -69,9 +70,10 @@ func (n GetSubTreeResponseBodyWrapper) GetMeta() []tree.Meta {
 }
 
 type ServiceClientGRPC struct {
-	key     *keys.PrivateKey
+	key        *keys.PrivateKey
-	log     *zap.Logger
+	log        *zap.Logger
-	clients []treeClient
+	clients    []treeClient
+	startIndex atomic.Int32
 }
 
 type treeClient struct {
@@ -330,12 +332,15 @@ func (c *ServiceClientGRPC) RemoveNode(ctx context.Context, bktInfo *data.Bucket
 type grpcFunc[Req any, Resp any] func(context.Context, Req, ...grpc.CallOption) (Resp, error)
 
 func requestWithRetry[Req any, Resp any](ctx context.Context, req Req, c *ServiceClientGRPC, fn func(client treeClient) grpcFunc[Req, Resp]) (res Resp, err error) {
-	for _, client := range c.clients {
+	start := int(c.startIndex.Load())
-		res, err = fn(client)(ctx, req)
+	for i := start; i < start+len(c.clients); i++ {
+		index := i % len(c.clients)
+		res, err = fn(c.clients[index])(ctx, req)
 		if !shouldTryAgain(err) {
+			c.startIndex.Store(int32(index))
 			return res, err
 		}
-		c.log.Debug("tree request error", zap.String("address", client.address), zap.Error(err))
+		c.log.Debug("tree request error", zap.String("address", c.clients[index].address), zap.Error(err))
 	}
 
 	return res, err
@@ -347,8 +352,14 @@ func shouldTryAgain(err error) bool {
 	}
 
 	code := status.Code(unwrapErr(err))
-	if code == codes.Unavailable || code == codes.Unimplemented ||
+	if code == codes.Unavailable || code == codes.Unimplemented {
-		strings.Contains(err.Error(), "not found") {
+		return true
+	}
+
+	errText := err.Error()
+	if strings.Contains(errText, "not found") ||
+		strings.Contains(errText, "shard is in read-only mode") ||
+		strings.Contains(errText, "shard is in degraded mode") {
 		return true
 	}
 

internal/frostfs/services/tree_client_grpc_test.go

@@ -1,11 +1,14 @@
 package services
 
 import (
+	"context"
 	"errors"
 	"testing"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/layer"
 	"github.com/stretchr/testify/require"
+	"go.uber.org/zap/zaptest"
+	"google.golang.org/grpc"
 )
 
 func TestHandleError(t *testing.T) {
@@ -33,3 +36,65 @@ func TestHandleError(t *testing.T) {
 		})
 	}
 }
+
+func TestRetry(t *testing.T) {
+	ctx := context.Background()
+
+	cl := &ServiceClientGRPC{
+		log: zaptest.NewLogger(t),
+		clients: []treeClient{
+			{address: "node0"},
+			{address: "node1"},
+			{address: "node2"},
+			{address: "node3"},
+		},
+	}
+
+	fn := func(client treeClient) grpcFunc[[]string, string] {
+		return func(ctx context.Context, shouldFail []string, opts ...grpc.CallOption) (string, error) {
+			for _, item := range shouldFail {
+				if item == client.address {
+					return "", errors.New("not found")
+				}
+			}
+			return client.address, nil
+		}
+	}
+
+	t.Run("first ok", func(t *testing.T) {
+		resp, err := requestWithRetry(ctx, []string{}, cl, fn)
+		require.NoError(t, err)
+		require.Equal(t, "node0", resp)
+		require.Equal(t, 0, int(cl.startIndex.Load()))
+		cl.startIndex.Store(0)
+	})
+
+	t.Run("first failed", func(t *testing.T) {
+		resp, err := requestWithRetry(ctx, []string{"node0"}, cl, fn)
+		require.NoError(t, err)
+		require.Equal(t, "node1", resp)
+		require.Equal(t, 1, int(cl.startIndex.Load()))
+		cl.startIndex.Store(0)
+	})
+
+	t.Run("all failed", func(t *testing.T) {
+		resp, err := requestWithRetry(ctx, []string{"node0", "node1", "node2", "node3"}, cl, fn)
+		require.Error(t, err)
+		require.Equal(t, "", resp)
+		require.Equal(t, 0, int(cl.startIndex.Load()))
+		cl.startIndex.Store(0)
+	})
+
+	t.Run("round", func(t *testing.T) {
+		resp, err := requestWithRetry(ctx, []string{"node0", "node1"}, cl, fn)
+		require.NoError(t, err)
+		require.Equal(t, "node2", resp)
+		require.Equal(t, 2, int(cl.startIndex.Load()))
+
+		resp, err = requestWithRetry(ctx, []string{"node2", "node3"}, cl, fn)
+		require.NoError(t, err)
+		require.Equal(t, "node0", resp)
+		require.Equal(t, 0, int(cl.startIndex.Load()))
+		cl.startIndex.Store(0)
+	})
+}