#CircuitBreaker

A utility for logically branching based on failure rates and/or counts

###Usage

Raw

var breaker = new CircuitBreaker({
  failure_rate: 0.5,
  failure_count: 10,
  reset_timeout: 30*1000
});

if (breaker.closed()) {
  doSomething("arg", function(err) {
    if (err) {
      breaker.fail();
      return;
    }

    breaker.pass();
    ... continue ...
  });
}

Wrapped Callback

var breaker = new CircuitBreaker({
  failure_rate: 0.5,
  failure_count: 10,
  reset_timeout: 30*1000
});

if (breaker.closed()) {
  doSomething("arg", breaker.monitor(function(err) {
    ... continue ...
  }));
}

Injected

var breaker = new CircuitBreaker({
  failure_rate: 0.5,
  failure_count: 10,
  reset_timeout: 30*1000,
  fn: doSomething
});

breaker.call("arg", function(err) {
  ... continue ...
});

###API

CircuitBreaker(options) Constructor

pass() Counts a success event.

fail() Counts a failure event.

open() Returns true if the circuit breaker is open and false otherwise.

closed() Return true if the circuit breaker is closed and false otherwise.

monitor([cb]) Wraps a callback. Calls fail if callback is called with an err and pass otherwise.

call([arg1[, arg2[, ...]]]) Calls injected fn with provided arguments if the breaker is closed. If last argument is a function, it is assumed to be a callback and is wrapped by monitor.

###Options

failure_rate Rate of failure required to trip the circuit breaker.

failure_count Failure count required to trip the circuit breaker.

reset_timeout Time in milliseconds to wait before reseting the circuit breaker once it has been tripped.

[fn] Function to be gated by the circuit breaker.