Ring buffer example.

ring_buffer.go

package main

import "fmt"

type RingBuffer struct {
	size   int
	buffer []int
	head   int
	tail   int
}

func NewRingBuffer(size int) *RingBuffer {
	buffer := make([]int, size)
	for i, _ := range buffer {
		buffer[i] = -1
	}

	return &RingBuffer{
		size:   size,
		buffer: buffer,
		head:   0,
		tail:   0,
	}
}

func (buffer *RingBuffer) Push(i int) error {
	// if current tail is free, use it
	if buffer.buffer[buffer.tail] == -1 {
		buffer.buffer[buffer.tail] = i
		return nil
	}

	// if not, move to next slot
	newTail := buffer.tail + 1

	// if next slot is last slot, reset to zero
	if buffer.tail == buffer.size-1 {
		newTail = 0
	}

	// if new tail is empty, use it
	if buffer.buffer[newTail] == -1 {
		buffer.buffer[newTail] = i
		buffer.tail = newTail
		return nil
	}

	return fmt.Errorf("Queue is full")
}

func (buffer *RingBuffer) Pop() (int, error) {
	if buffer.buffer[buffer.head] != -1 {
		i := buffer.buffer[buffer.head]
		buffer.buffer[buffer.head] = -1
		if buffer.head+1 < buffer.size {
			buffer.head++
		} else {
			buffer.head = 0
		}
		return i, nil
	}

	return -1, fmt.Errorf("Head is empty")
}

func main() {
	size := 10
	buffer := NewRingBuffer(size)
	buffer.Push(1)
	buffer.Push(2)
	buffer.Push(3)
	buffer.Push(4)
	buffer.Push(5)

	buffer.Pop()
	buffer.Pop()
	buffer.Pop()

	buffer.Push(6)
	buffer.Push(7)
	buffer.Push(8)

	buffer.Pop()

	fmt.Printf("%#v\n", buffer.buffer)
}