[GitHub] [dubbo-go] watermelo commented on a change in pull request #748: Ftr: add sentinel-golang flow control/circuit breaker

[GitBox <gi...@apache.org>]

watermelo commented on a change in pull request #748:
URL: https://github.com/apache/dubbo-go/pull/748#discussion_r487032954



##########
File path: filter/filter_impl/sentinel_filter.go
##########
@@ -0,0 +1,226 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 filter_impl
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+)
+
+import (
+	sentinel "github.com/alibaba/sentinel-golang/api"
+	"github.com/alibaba/sentinel-golang/core/base"
+)
+
+import (
+	"github.com/apache/dubbo-go/common"
+	"github.com/apache/dubbo-go/common/constant"
+	"github.com/apache/dubbo-go/common/extension"
+	"github.com/apache/dubbo-go/filter"
+	"github.com/apache/dubbo-go/protocol"
+)
+
+func init() {
+	extension.SetFilter(SentinelProviderFilterName, GetSentinelProviderFilter)
+	extension.SetFilter(SentinelConsumerFilterName, GetSentinelConsumerFilter)
+}
+
+func GetSentinelConsumerFilter() filter.Filter {
+	return &SentinelConsumerFilter{}
+}
+
+func GetSentinelProviderFilter() filter.Filter {
+	return &SentinelProviderFilter{}
+}
+
+type SentinelProviderFilter struct{}
+
+func (d *SentinelProviderFilter) Invoke(ctx context.Context, invoker protocol.Invoker, invocation protocol.Invocation) protocol.Result {
+	methodResourceName := getResourceName(invoker, invocation, getProviderPrefix())
+	interfaceResourceName := ""
+	if getInterfaceGroupAndVersionEnabled() {
+		interfaceResourceName = getColonSeparatedKey(invoker.GetUrl())
+	} else {
+		interfaceResourceName = invoker.GetUrl().Service()
+	}
+	var (
+		interfaceEntry *base.SentinelEntry
+		methodEntry    *base.SentinelEntry
+		b              *base.BlockError
+	)
+	interfaceEntry, b = sentinel.Entry(interfaceResourceName, sentinel.WithResourceType(base.ResTypeRPC), sentinel.WithTrafficType(base.Inbound))
+	if b != nil {
+		// interface blocked
+		return sentinelDubboProviderFallback(ctx, invoker, invocation, b)
+	}
+	ctx = context.WithValue(ctx, InterfaceEntryKey, interfaceEntry)
+
+	methodEntry, b = sentinel.Entry(methodResourceName, sentinel.WithResourceType(base.ResTypeRPC),
+		sentinel.WithTrafficType(base.Inbound), sentinel.WithArgs(invocation.Arguments()...))
+	if b != nil {
+		// method blocked
+		return sentinelDubboProviderFallback(ctx, invoker, invocation, b)
+	}
+	ctx = context.WithValue(ctx, MethodEntryKey, methodEntry)
+	return invoker.Invoke(ctx, invocation)
+}
+
+func (d *SentinelProviderFilter) OnResponse(ctx context.Context, result protocol.Result, _ protocol.Invoker, _ protocol.Invocation) protocol.Result {
+	if methodEntry := ctx.Value(MethodEntryKey); methodEntry != nil {
+		e := methodEntry.(*base.SentinelEntry)
+		sentinel.TraceError(e, result.Error())
+		e.Exit()
+	}
+	if interfaceEntry := ctx.Value(InterfaceEntryKey); interfaceEntry != nil {
+		e := interfaceEntry.(*base.SentinelEntry)
+		sentinel.TraceError(e, result.Error())
+		e.Exit()
+	}
+	return result
+}
+
+type SentinelConsumerFilter struct{}
+
+func (d *SentinelConsumerFilter) Invoke(ctx context.Context, invoker protocol.Invoker, invocation protocol.Invocation) protocol.Result {
+	methodResourceName := getResourceName(invoker, invocation, getConsumerPrefix())
+	interfaceResourceName := ""
+	if getInterfaceGroupAndVersionEnabled() {
+		interfaceResourceName = getColonSeparatedKey(invoker.GetUrl())
+	} else {
+		interfaceResourceName = invoker.GetUrl().Service()
+	}
+	var (
+		interfaceEntry *base.SentinelEntry
+		methodEntry    *base.SentinelEntry
+		b              *base.BlockError
+	)
+
+	interfaceEntry, b = sentinel.Entry(interfaceResourceName, sentinel.WithResourceType(base.ResTypeRPC), sentinel.WithTrafficType(base.Outbound))
+	if b != nil {
+		// interface blocked
+		return sentinelDubboConsumerFallback(ctx, invoker, invocation, b)
+	}
+	ctx = context.WithValue(ctx, InterfaceEntryKey, interfaceEntry)
+
+	methodEntry, b = sentinel.Entry(methodResourceName, sentinel.WithResourceType(base.ResTypeRPC),
+		sentinel.WithTrafficType(base.Outbound), sentinel.WithArgs(invocation.Arguments()...))
+	if b != nil {
+		// method blocked
+		return sentinelDubboConsumerFallback(ctx, invoker, invocation, b)
+	}
+	ctx = context.WithValue(ctx, MethodEntryKey, methodEntry)
+
+	return invoker.Invoke(ctx, invocation)
+}
+
+func (d *SentinelConsumerFilter) OnResponse(ctx context.Context, result protocol.Result, _ protocol.Invoker, _ protocol.Invocation) protocol.Result {
+	if methodEntry := ctx.Value(MethodEntryKey); methodEntry != nil {
+		e := methodEntry.(*base.SentinelEntry)
+		sentinel.TraceError(e, result.Error())
+		e.Exit()
+	}
+	if interfaceEntry := ctx.Value(InterfaceEntryKey); interfaceEntry != nil {
+		e := interfaceEntry.(*base.SentinelEntry)
+		sentinel.TraceError(e, result.Error())
+		e.Exit()
+	}
+	return result
+}
+
+var (
+	sentinelDubboConsumerFallback = getDefaultDubboFallback()
+	sentinelDubboProviderFallback = getDefaultDubboFallback()
+)
+
+type DubboFallback func(context.Context, protocol.Invoker, protocol.Invocation, *base.BlockError) protocol.Result
+
+func SetDubboConsumerFallback(f DubboFallback) {
+	sentinelDubboConsumerFallback = f
+}
+func SetDubboProviderFallback(f DubboFallback) {
+	sentinelDubboProviderFallback = f
+}
+func getDefaultDubboFallback() DubboFallback {
+	return func(ctx context.Context, invoker protocol.Invoker, invocation protocol.Invocation, blockError *base.BlockError) protocol.Result {
+		result := &protocol.RPCResult{}
+		result.SetResult(nil)
+		result.SetError(blockError)
+		return result
+	}
+}
+
+const (
+	SentinelProviderFilterName = "sentinel-provider"
+	SentinelConsumerFilterName = "sentinel-consumer"
+
+	DefaultProviderPrefix = "dubbo:provider:"
+	DefaultConsumerPrefix = "dubbo:consumer:"
+
+	MethodEntryKey    = "$$sentinelMethodEntry"
+	InterfaceEntryKey = "$$sentinelInterfaceEntry"
+)
+
+// Currently, a ConcurrentHashMap mechanism is missing.
+// All values are filled with default values first.
+
+func getResourceName(invoker protocol.Invoker, invocation protocol.Invocation, prefix string) string {
+	var (
+		buf               bytes.Buffer

Review comment:
       Maybe it's more efficient to use strings.Builder to replace bytes.Buffer.




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