Value alignment issue on 32-bit systems (ARM)

[abferm]

This library suffers from go issue #599 when compiled for ARM using the gc compiler. The gccgo compiler appears to take care of it, but that limits the go version to <=1.6.1 for official gccgo releases. The following padding & reordering of the Breaker struct fixes the issue.

`// Breaker is the base of a circuit breaker. It maintains failure and success counters
// as well as the event subscribers.
type Breaker struct {
// BackOff is the backoff policy that is used when determining if the breaker should
// attempt to retry. A breaker created with NewBreaker will use an exponential backoff
// policy by default.
BackOff backoff.BackOff

// ShouldTrip is a TripFunc that determines whether a Fail() call should trip the breaker.
// A breaker created with NewBreaker will not have a ShouldTrip by default, and thus will
// never automatically trip.
ShouldTrip TripFunc

// Clock is used for controlling time in tests.
Clock clock.Clock

_              [4]byte // pad to fix golang issue #599
consecFailures int64
lastFailure    int64 // stored as nanoseconds since the Unix epoch
halfOpens      int64
counts         *window
nextBackOff    time.Duration
tripped        int32
broken         int32
eventReceivers []chan BreakerEvent
listeners      []chan ListenerEvent
backoffLock    sync.Mutex

}`

[abferm]

The issue also presents itself in 386 binaries. The issue can be demonstrated by compiling the following code for a 64-bit system and a 32-bit system and running both. Switching the import to my fork will make the code work for both 32-bit and 64-bit systems.

package main

import (
	"log"

	circuit "github.com/rubyist/circuitbreaker"
)

func main() {
	cb := circuit.NewThresholdBreaker(10)
	events := cb.Subscribe()
	go func() {
		for {
			e := <-events
			// Monitor breaker events like BreakerTripped, BreakerReset, BreakerFail, BreakerReady
			log.Println(e)
		}
	}()

	cb.Success()
	cb.Fail()
	cb.Reset()
}