feat:degradation (#6)

* feat:degradation

* fix:License header,readme link

.github/workflows/pr-check.yml

@@ -9,7 +9,7 @@ jobs:
       - uses: actions/checkout@v3
 
       - name: Check License Header
-        uses: apache/skywalking-eyes/header@main
+        uses: apache/skywalking-eyes/header@v0.4.0
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 

README.md

@@ -288,7 +288,24 @@ The echo method uses the following configuration (0.3, 100) and other methods us
   }
 }
 ```
+##### Degradation: Category=degradation
 
+
+| Variable   | Introduction                       |
+|------------|------------------------------------|
+| enable     | Whether to enable degradation      |
+| percentage | The percentage of dropped requests | 
+
+Example：
+
+> configPath: /KitexConfig/ClientName/ServiceName/degradation
+```json
+{
+  "enable": true,
+  "percentage": 30
+}
+```
+Note: Degradation is not enabled by default.
 ### More Info
 
 Refer to [example](https://github.com/kitex-contrib/config-consul/tree/main/example) for more usage.

README_CN.md

@@ -289,6 +289,25 @@ echo 方法使用下面的配置（0.3、100），其他方法使用全局默认
 }
 ```
 
+##### 降级: Category=degradation
+
+| 参数         | 说明       |
+|------------|----------|
+| enable     | 是否开启降级策略 |
+| percentage | 丢弃请求的比例  | 
+
+例子：
+
+> configPath: /KitexConfig/ClientName/ServiceName/degradation
+
+```json
+{
+  "enable": true,
+  "percentage": 30
+}
+```
+
+注：默认不开启降级（enable为false）
 ### 更多信息
 
 更多示例请参考 [example](https://github.com/kitex-contrib/config-consul/tree/main/example)

client/degradation.go

@@ -0,0 +1,62 @@
+// Copyright 2024 CloudWeGo 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 client
+
+import (
+	"github.com/cloudwego/kitex/client"
+	"github.com/cloudwego/kitex/pkg/klog"
+	"github.com/kitex-contrib/config-consul/consul"
+	"github.com/kitex-contrib/config-consul/pkg/degradation"
+	"github.com/kitex-contrib/config-consul/utils"
+)
+
+func WithDegradation(dest, src string, consulClient consul.Client, uniqueID int64, opts utils.Options) []client.Option {
+	param, err := consulClient.ClientConfigParam(&consul.ConfigParamConfig{
+		Category:          degradationConfigName,
+		ServerServiceName: dest,
+		ClientServiceName: src,
+	})
+	if err != nil {
+		panic(err)
+	}
+	for _, f := range opts.ConsulCustomFunctions {
+		f(&param)
+	}
+	key := param.Prefix + "/" + param.Path
+	container := initDegradationOptions(param.Type, key, dest, uniqueID, consulClient)
+	return []client.Option{
+		client.WithACLRules(container.GetAclRule()),
+		client.WithCloseCallbacks(func() error {
+			// cancel the configuration listener when client is closed.
+			consulClient.DeregisterConfig(key, uniqueID)
+			return nil
+		}),
+	}
+}
+
+func initDegradationOptions(configType consul.ConfigType, key, dest string, uniqueID int64, consulClient consul.Client) *degradation.DegradationContainer {
+	container := degradation.NewDegradationContainer()
+	onChangeCallback := func(data string, parser consul.ConfigParser) {
+		config := &degradation.DegradationConfig{}
+		err := parser.Decode(configType, data, config)
+		if err != nil {
+			klog.Warnf("[consul] %s server consul degradation config: unmarshal data %s failed: %s, skip...", key, data, err)
+			return
+		}
+		container.NotifyPolicyChange(config)
+	}
+	consulClient.RegisterConfigCallback(key, uniqueID, onChangeCallback)
+	return container
+}

client/suite.go

@@ -25,6 +25,7 @@ const (
 	retryConfigName          = "retry"
 	rpcTimeoutConfigName     = "rpc_timeout"
 	circuitBreakerConfigName = "circuit_break"
+	degradationConfigName    = "degradation"
 )
 
 type ConsulClientSuite struct {
@@ -59,5 +60,6 @@ func (s *ConsulClientSuite) Options() []client.Option {
 	opts = append(opts, WithCircuitBreaker(s.service, s.client, s.consulClient, s.uid, s.opts)...)
 	opts = append(opts, WithRetryPolicy(s.service, s.client, s.consulClient, s.uid, s.opts)...)
 	opts = append(opts, WithRPCTimeout(s.service, s.client, s.consulClient, s.uid, s.opts)...)
+	opts = append(opts, WithDegradation(s.service, s.client, s.consulClient, s.uid, s.opts)...)
 	return opts
 }

pkg/degradation/item_degradation.go

@@ -0,0 +1,81 @@
+// Copyright 2024 CloudWeGo 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 degradation
+
+import (
+	"context"
+	"errors"
+	"sync/atomic"
+
+	"github.com/bytedance/gopkg/lang/fastrand"
+	"github.com/cloudwego/configmanager/iface"
+	"github.com/cloudwego/kitex/pkg/acl"
+)
+
+var errRejected = errors.New("rejected by client degradation config")
+
+var defaultDegradationConfig = &DegradationConfig{
+	Enable:     false,
+	Percentage: 0,
+}
+
+type DegradationConfig struct {
+	Enable     bool `json:"enable"`
+	Percentage int  `json:"percentage"`
+}
+
+// DeepCopy returns a copy of the current DegradationConfig
+func (c *DegradationConfig) DeepCopy() iface.ConfigValueItem {
+	result := &DegradationConfig{
+		Enable:     c.Enable,
+		Percentage: c.Percentage,
+	}
+	return result
+}
+
+// EqualsTo returns true if the current DegradationConfig equals to the other DegradationConfig
+func (c *DegradationConfig) EqualsTo(other iface.ConfigValueItem) bool {
+	o := other.(*DegradationConfig)
+	return c.Enable == o.Enable && c.Percentage == o.Percentage
+}
+
+// DegradationContainer is a wrapper for DegradationConfig
+type DegradationContainer struct {
+	config atomic.Value
+}
+
+func NewDegradationContainer() *DegradationContainer {
+	c := &DegradationContainer{}
+	c.config.Store(defaultDegradationConfig)
+	return c
+}
+
+// NotifyPolicyChange to receive policy when it changes
+func (c *DegradationContainer) NotifyPolicyChange(cfg *DegradationConfig) {
+	c.config.Store(cfg)
+}
+
+func (c *DegradationContainer) GetAclRule() acl.RejectFunc {
+	return func(ctx context.Context, request interface{}) (reason error) {
+		cfg := c.config.Load().(*DegradationConfig)
+		if !cfg.Enable {
+			return nil
+		}
+		if fastrand.Intn(100) < cfg.Percentage {
+			return errRejected
+		}
+		return nil
+	}
+}

pkg/degradation/item_degradation_test.go

@@ -0,0 +1,40 @@
+// Copyright 2024 CloudWeGo 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 degradation
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/cloudwego/kitex/pkg/acl"
+	"github.com/cloudwego/thriftgo/pkg/test"
+)
+
+var errFake = errors.New("fake error")
+
+func invoke(ctx context.Context, request, response interface{}) error {
+	return errFake
+}
+
+func TestNewContainer(t *testing.T) {
+	container := NewDegradationContainer()
+	aclMiddleware := acl.NewACLMiddleware([]acl.RejectFunc{container.GetAclRule()})
+	test.Assert(t, errors.Is(aclMiddleware(invoke)(context.Background(), nil, nil), errFake))
+	container.NotifyPolicyChange(&DegradationConfig{Enable: false, Percentage: 100})
+	test.Assert(t, errors.Is(aclMiddleware(invoke)(context.Background(), nil, nil), errFake))
+	container.NotifyPolicyChange(&DegradationConfig{Enable: true, Percentage: 100})
+	test.Assert(t, errors.Is(aclMiddleware(invoke)(context.Background(), nil, nil), errRejected))
+}

server/suit.go

@@ -49,7 +49,7 @@ func NewSuite(service string, cli consul.Client,
 	return su
 }
 
-// Options return a list client.Option
+// Options return a list server.Option
 func (s *ConsulServerSuite) Options() []server.Option {
 	opts := make([]server.Option, 0, 2)
 	opts = append(opts, WithLimiter(s.service, s.consulClient, s.uid, s.opts))