mirror of
https://github.com/crazybber/go-pattern-examples.git
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107 lines
2.7 KiB
Go
107 lines
2.7 KiB
Go
/*
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* @Description: https://github.com/crazybber
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* @Author: Edward
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* @Date: 2020-05-10 22:00:58
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* @Last Modified by: Edward
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* @Last Modified time: 2020-05-21 17:41:46
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*/
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package circuit
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import (
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"errors"
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"fmt"
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"sync"
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"time"
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)
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////////////////////////////////
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///使用HTTP请求的例子
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//每个搜索引擎时时刻刻都会遇到超大规模的请求的流量.
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//这里演示一个复杂一点的例子，同时使用Option 模式
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//ErrServiceUnavailable for error
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var (
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ErrTooManyRequests = errors.New("too many requests")
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ErrServiceUnavailable = errors.New("service unavailable")
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FailureThreshold = 10 //最大失败次数--->失败阈值
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)
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// 默认的超时时间
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const (
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defaultTimeout = time.Second * 30
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defaultSuccessThreshold = 2
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)
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////////////////////////////////
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/// 状态计数器 用以维护断路器内部的状态
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/// 无论是对象式断路器还是函数式断路器
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/// 都要用到计数器
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////////////////////////////////
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//State 断路器本身的状态的
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//State of switch int
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type State int
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// state for breaker
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const (
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StateClosed State = iota //默认的闭合状态，可以正常执行业务
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StateHalfOpen
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StateOpen
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)
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////////////////////////////////
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//way 1 对象式断路器
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////////////////////////////////
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//RequestBreaker for protection
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type RequestBreaker struct {
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options Options
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mutex sync.Mutex
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state OperationState //断路器的当前状态
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generation uint64
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counts ICounter
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}
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//NewRequestBreaker return a breaker
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func NewRequestBreaker(opts ...Option) *RequestBreaker {
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defaultOptions := Options{
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Name: "defaultBreakerName",
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Expiry: time.Now().Add(time.Second * 20),
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Interval: time.Second * 2, // interval to check status
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Timeout: time.Second * 60, //default to 60 seconds
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MaxRequests: 5,
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WhenToBreak: func(counts counters) bool { return counts.ConsecutiveFailures > 2 },
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OnStateChanged: func(name string, fromPre State, toCurrent State) {},
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}
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for _, setOption := range opts {
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setOption(&defaultOptions)
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}
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return &RequestBreaker{
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options: defaultOptions,
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counts: &counters{},
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generation: 0,
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}
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}
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// Do the given requested work if the RequestBreaker accepts it.
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// Do returns an error instantly if the RequestBreaker rejects the request.
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// Otherwise, Execute returns the result of the request.
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// If a panic occurs in the request, the RequestBreaker handles it as an error and causes the same panic again.
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func (rb *RequestBreaker) Do(work func() (interface{}, error)) (interface{}, error) {
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//before
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fmt.Println("before do : request:", rb.counts.Total())
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//do work from requested user
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result, err := work()
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fmt.Println("after do : request:", rb.counts.Total())
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return result, err
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}
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