Breaking API changes and lookup method for observing running servers

Author: nexcode

attributes/attributes.go

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2025 RPCPlatform Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package attributes
+
+// New returns attributes with default values.
+func New() *Attributes {
+	return &Attributes{
+		BalancerWeight: 1,
+	}
+}
+
+// Attributes provides server attribute values.
+type Attributes struct {
+	BalancerPriority int
+	BalancerWeight   int
+}

options/make.go attributes/attributes_load.gooptions/make.go renamed to attributes/attributes_load.go

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022 RPCPlatform Authors
+ * Copyright 2025 RPCPlatform Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,22 +14,20 @@
  * limitations under the License.
  */
 
-package options
+package attributes
 
-import (
-	"github.com/nexcode/rpcplatform/internal/config"
-	etcd "go.etcd.io/etcd/client/v3"
-)
+import "strconv"
 
-func Make(etcdClient *etcd.Client, etcdPrefix string, options []Option) *config.Config {
-	config := &config.Config{
-		EtcdClient: etcdClient,
-		EtcdPrefix: etcdPrefix,
+// Load used internally to load keys and values from strings.
+func (sa *Attributes) Load(key, value string) {
+	switch key {
+	case balancerPriority:
+		if v, err := strconv.Atoi(value); err == nil {
+			sa.BalancerPriority = v
+		}
+	case balancerWeight:
+		if v, err := strconv.Atoi(value); err == nil {
+			sa.BalancerWeight = v
+		}
 	}
-
-	for _, option := range options {
-		option.apply(config)
-	}
-
-	return config
 }

attributes/attributes_values.go

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2025 RPCPlatform Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package attributes
+
+import "strconv"
+
+// Values used internally to create an string array of keys and values.
+func (sa *Attributes) Values() []string {
+	return []string{
+		balancerPriority, strconv.Itoa(sa.BalancerPriority),
+		balancerWeight, strconv.Itoa(sa.BalancerWeight),
+	}
+}

errors/errors.go attributes/const.goerrors/errors.go renamed to attributes/const.go

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022 RPCPlatform Authors
+ * Copyright 2025 RPCPlatform Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,10 +14,9 @@
  * limitations under the License.
  */
 
-package errors
+package attributes
 
-import "errors"
-
-var (
-	ErrGRPCOptionsExpected = errors.New("*[]grpc.DialOption or *[]grpc.ServerOption expected")
+const (
+	balancerPriority = "balancerPriority"
+	balancerWeight   = "balancerWeight"
 )

attributes_server.go

@@ -17,14 +17,12 @@
 package rpcplatform
 
 import (
-	etcd "go.etcd.io/etcd/client/v3"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/resolver/manual"
 )
 
 type Client struct {
 	target   string
-	etcd     *etcd.Client
 	client   *grpc.ClientConn
 	resolver *manual.Resolver
 }

client.go

@@ -17,26 +17,21 @@
 package rpcplatform
 
 import (
+	"github.com/nexcode/rpcplatform/internal/serverinfo"
+	"google.golang.org/grpc/attributes"
 	"google.golang.org/grpc/resolver"
 )
 
-func (c *Client) updateState(init bool, serverInfo map[string]string) {
-	tree := c.makeServerInfo(serverInfo)
-
+func (c *Client) updateState(init bool, serverInfoTree map[string]*serverinfo.ServerInfo) {
 	state := resolver.State{
-		Addresses: make([]resolver.Address, 0, len(tree)),
+		Addresses: make([]resolver.Address, 0, len(serverInfoTree)),
 	}
 
-	for _, value := range tree {
-		address := resolver.Address{
-			Addr: value.address,
-		}
-
-		for key, value := range value.attributes {
-			address.Attributes = address.Attributes.WithValue(key, value)
-		}
-
-		state.Addresses = append(state.Addresses, address)
+	for _, value := range serverInfoTree {
+		state.Addresses = append(state.Addresses, resolver.Address{
+			Addr:       value.Address,
+			Attributes: attributes.New(struct{}{}, value.Attributes),
+		})
 	}
 
 	if init {

client_stateinit.go

@@ -1,28 +1,25 @@
 ## Adding attributes
 
-This example is very similar to [QuickStart](../quickstart), but now we will use additional attributes for client and server.
+This example is very similar to [QuickStart](../quickstart), but now we will use additional attributes for server.
 
 For the client, we will set the maximum number of active servers (all other servers above this value will be backup servers):
 
 ```go
-attributes := rpcplatform.Attributes().Client()
-attributes.SetMaxActiveServers(2)
-
-client, err := rpcp.NewClient("server", attributes)
+client, err := rpcp.NewClient("server", options.Client.MaxActiveServers(2))
 if err != nil {
-    panic(err)
+	panic(err)
 }
 ```
 
-And for the server we will set the balancing weight:
+And for the server we will set the balancing weight attribute:
 
 ```go
-attributes := rpcplatform.Attributes().Server()
-attributes.SetBalancerWeight(4)
+attributes := attributes.New()
+attributes.BalancerWeight = 4
 
-server, err := rpcp.NewServer("server", "localhost:", attributes)
+server, err := rpcp.NewServer("server", "localhost:", options.Server.Attributes(attributes))
 if err != nil {
-    panic(err)
+	panic(err)
 }
 ```