Simple Disruptor Example

disruptor.go

package main

import (
	"fmt"
	"runtime"
	"time"
)

// the code below is loosely based upon: https://gist.github.com/tux21b/1218360
// it is only safe on 64-bit CPUs.

const BufferSize = 1024 * 16
const BufferMask = BufferSize - 1
const Iterations int64 = 1000000 * 100

var ring [BufferSize]int64

type Cursor struct {
	value   int64
	padding [7]int64
}

func main() {
	runtime.GOMAXPROCS(2)

	var readerBarrier, writerBarrier Cursor

	started := time.Now()

	go func() {
		for sequence, cachedGate := int64(0), int64(0); sequence < Iterations; sequence++ {
			for sequence >= cachedGate {
				cachedGate = readerBarrier.value + BufferSize
			}

			ring[sequence&BufferMask] = sequence
			writerBarrier.value = sequence + 1
		}
	}()

	for sequence, cachedGate := int64(0), int64(0); sequence < Iterations; sequence++ {
		for sequence >= cachedGate {
			cachedGate = writerBarrier.value
		}

		message := ring[sequence&BufferMask]
		readerBarrier.value = sequence
		if message != sequence {
			panic("Out of sequence")
		}
	}

	finished := time.Now()
	fmt.Println(Iterations, "send/receive operations in", finished.Sub(started))
}