@scintillate/circuit-breaker

A simple circuit breaker for TypeScript.

Installation

npm install --save @scintillate/circuit-breaker

Usage

Basic Usage

import { CircuitBreaker } from '@scintillate/circuit-breaker';

class Test {
  @CircuitBreaker()
  async callService(): Promise<any> {
    // ...
  }
};

Options

export interface Options {
  // Cooldown period before retrying in milliseconds.
  cooldownPeriod?: number;
  // Retry count, before giving up.
  failureThreshold?: number;
  // Maximum cooldown period in milliseconds.
  maxCooldownPeriod?: number;
}

...
@CircuitBreaker({
  cooldownPeriod: 1000, // 1 second
  failureThreshold: 5,
  maxCooldownPeriod: 30 * 1000 // 30 seconds
})
...

The library does not automatically retry function execution. It depends on your application calling the function. If the function throws an exception failureThreshold times consecutively, the circuit goes into an open state. Consequent calls to the function will return undefined (or Promises will resolve to undefined) until cooldownPeriod has elapsed. cooldownPeriod increases exponentially with each subsequent failure to a maximum of maxCooldownPeriod.

Note that exceptions are not propagated.