A self configuring circuit breaker in Go
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README.md
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smartcb_test.go

README.md

Self-Configuring Smart Circuit Breaker

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A circuit breaker that continuously adjusts itself according to the error rate profile of the protected task and configures the right tripping threshold as needed.

Package smartcb provides a circuit breaker based on https://github.com/rubyist/circuitbreaker that automatically adjusts the tripping error threshold based on abnormal increase in error rate. All you need to tell it is the nominal QPS ("queries per second") for your task and it automatically sets the best values for adjusting the circuit breaker's responsiveness. If you want, you can adjust the circuit breaker's sensitivity as per your situation.

The circuit breaker starts off with a learning phase for understanding the error profile of the wrapped command and then adjusts its tripping threshold for error rate based on what it has learned.

The error threshold is calculated as an exponential weighted moving average which smoothens out jitter and can detect rapid changes in error rate, allowing for the circuit to trip fast in case of a rapid degradation of the wrapped command.

Installation

    go get github.com/codemartial/smartcb

Usage

package main

import (
	"log"
	"time"

	"github.com/codemartial/smartcb"
)

func main() {
	taskQPS := 1000

	st := smartcb.NewSmartTripper(taskQPS, smartcb.NewPolicies())
	scb := smartcb.NewSmartCircuitBreaker(st)

	if scb.Call(protectedTask, 0) != nil && scb.Tripped() {
		log.Println("Circuit Breaker tripped at error rate", scb.ErrorRate(), "Normal error rate was ", st.LearnedRate())
	}
}

Testing and Simulation

Run go test as usual to execute the unit tests. The package also includes a couple of simulations for slowly increasing error rates and fluctuating error rates that compare the state of SmartCB against Rate based circuit breaker from github.com/rubyist/circuitbreaker. To run these simulations use the following command:

    go test -tags sims