| /* |
| * 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 p2c |
| |
| import ( |
| "errors" |
| "fmt" |
| "math/rand" |
| "sync" |
| "time" |
| ) |
| |
| import ( |
| "github.com/dubbogo/gost/log/logger" |
| ) |
| |
| import ( |
| "dubbo.apache.org/dubbo-go/v3/cluster/loadbalance" |
| "dubbo.apache.org/dubbo-go/v3/cluster/metrics" |
| "dubbo.apache.org/dubbo-go/v3/common/constant" |
| "dubbo.apache.org/dubbo-go/v3/common/extension" |
| "dubbo.apache.org/dubbo-go/v3/protocol" |
| ) |
| |
| var ( |
| randSeed = func() int64 { |
| return time.Now().Unix() |
| } |
| ) |
| |
| func init() { |
| rand.Seed(randSeed()) |
| extension.SetLoadbalance(constant.LoadBalanceKeyP2C, newP2CLoadBalance) |
| } |
| |
| var ( |
| once sync.Once |
| instance loadbalance.LoadBalance |
| ) |
| |
| type p2cLoadBalance struct{} |
| |
| func newP2CLoadBalance() loadbalance.LoadBalance { |
| if instance == nil { |
| once.Do(func() { |
| instance = &p2cLoadBalance{} |
| }) |
| } |
| return instance |
| } |
| |
| func (l *p2cLoadBalance) Select(invokers []protocol.Invoker, invocation protocol.Invocation) protocol.Invoker { |
| if len(invokers) == 0 { |
| return nil |
| } |
| if len(invokers) == 1 { |
| return invokers[0] |
| } |
| // m is the Metrics, which saves the metrics of instance, invokers and methods |
| // The local metrics is available only for the earlier version. |
| m := metrics.LocalMetrics |
| // picks two nodes randomly |
| var i, j int |
| if len(invokers) == 2 { |
| i, j = 0, 1 |
| } else { |
| i = rand.Intn(len(invokers)) |
| j = i |
| for i == j { |
| j = rand.Intn(len(invokers)) |
| } |
| } |
| logger.Debugf("[P2C select] Two invokers were selected, invoker[%d]: %s, invoker[%d]: %s.", |
| i, invokers[i], j, invokers[j]) |
| |
| methodName := invocation.ActualMethodName() |
| // remainingIIface, remainingJIface means remaining capacity of node i and node j. |
| // If one of the metrics is empty, invoke the invocation to that node directly. |
| remainingIIface, err := m.GetMethodMetrics(invokers[i].GetURL(), methodName, metrics.HillClimbing) |
| if err != nil { |
| if errors.Is(err, metrics.ErrMetricsNotFound) { |
| logger.Debugf("[P2C select] The invoker[%d] was selected, because it hasn't been selected before.", i) |
| return invokers[i] |
| } |
| logger.Warnf("get method metrics err: %v", err) |
| return nil |
| } |
| |
| // TODO(justxuewei): It should have a strategy to drop some metrics after a period of time. |
| remainingJIface, err := m.GetMethodMetrics(invokers[j].GetURL(), methodName, metrics.HillClimbing) |
| if err != nil { |
| if errors.Is(err, metrics.ErrMetricsNotFound) { |
| logger.Debugf("[P2C select] The invoker[%d] was selected, because it hasn't been selected before.", j) |
| return invokers[j] |
| } |
| logger.Warnf("get method metrics err: %v", err) |
| return nil |
| } |
| |
| // Convert interface to int, if the type is unexpected, panic immediately |
| remainingI, ok := remainingIIface.(uint64) |
| if !ok { |
| panic(fmt.Sprintf("[P2C select] the type of %s expects to be uint64, but gets %T", |
| metrics.HillClimbing, remainingIIface)) |
| } |
| |
| remainingJ, ok := remainingJIface.(uint64) |
| if !ok { |
| panic(fmt.Sprintf("the type of %s expects to be uint64, but gets %T", metrics.HillClimbing, remainingJIface)) |
| } |
| |
| logger.Debugf("[P2C select] The invoker[%d] remaining is %d, and the invoker[%d] is %d.", i, remainingI, j, remainingJ) |
| |
| // For the remaining capacity, the bigger, the better. |
| if remainingI > remainingJ { |
| logger.Debugf("[P2C select] The invoker[%d] was selected.", i) |
| return invokers[i] |
| } |
| |
| logger.Debugf("[P2C select] The invoker[%d] was selected.", j) |
| return invokers[j] |
| } |