𝗖𝗶𝗿𝗰𝘂𝗶𝘁 𝗕𝗿𝗲𝗮𝗸𝗲𝗿 𝗘𝘅𝗽𝗹𝗮𝗶𝗻𝗲𝗱 𝗧𝗵𝗿𝗼𝘂𝗴𝗵 𝗙𝗮𝗶𝗹𝘂𝗿𝗲

𝗖𝗶𝗿𝗰𝘂𝗶𝘁 𝗕𝗿𝗲𝗮𝗸𝗲𝗿 𝗘𝘅𝗽𝗹𝗮𝗶𝗻𝗲𝗱 𝗧𝗵𝗿𝗼𝘂𝗴𝗵 𝗙𝗮𝗶𝗹𝘂𝗿𝗲

I faced an unexpected problem a few days ago.

Frustration hit me hard. I wanted to fix it. Curiosity forced me to keep going.

I sat down with the problem again. I found the solution. It is called a circuit breaker.

In software, a circuit breaker prevents a single failure from crashing your entire system. It works like the breaker in your home.

A circuit breaker has three states:

• CLOSED: Everything works. All requests go through. The system tracks failures. If failures hit a limit, the circuit opens.
• OPEN: The system stops all requests immediately. This gives the failing service time to recover.
• HALF_OPEN: The system allows a few test requests. If they succeed, the circuit closes. If they fail, the circuit opens again.

Here is a simple implementation in code:

export class CircuitBreaker { constructor(failureThreshold, cooldownMs) { this.failureThreshold = failureThreshold this.cooldownMs = cooldownMs this.state = "CLOSED" this.failureCount = 0 this.lastFailureTime = null }

openCircuit() {
    this.state = "OPEN"
    this.lastFailureTime = Date.now()
}

closeCircuit() {
    this.state = "CLOSED"
    this.failureCount = 0
    this.lastFailureTime = null
}

halfOpenCircuit() {
    this.state = "HALF_OPEN"
}

async execute(fn) {
    if (this.state === "OPEN") {
        const cooldownExpired = Date.now() - this.lastFailureTime >= this.cooldownMs
        if (!cooldownExpired) {
            throw new Error("Circuit is open.")
        }
        this.halfOpenCircuit();
    }

    try {
        const result = await fn()
        if (this.state === "HALF_OPEN") {
            this.closeCircuit()
        }
        return result;
    } catch (error) {
        if (this.state === "HALF_OPEN") {
            this.openCircuit()
            throw error;
        }
        this.failureCount++
        if (this.failureCount >= this.failureThreshold) {
            this.openCircuit()
        }
        throw error
    }
}

}

This mechanism fixed my recent issue. It stops the flood of errors from killing your application.

Please share your thoughts in the comments. I am still learning.

Source: https://dev.to/neel-vekariya/circuit-breaker-explained-through-real-failure-experience-3aeg