fifo

fifo

This package provides thread safe unique use case FIFO structures.

Ring

Ring provides a fixed-length FIFO linked-list style ring structure. Push() adds new elements to the ring, and Pop() removes the oldest element from the ring. When the ring reaches the specified max lengh, a Push() operation will first remove the oldest element before adding the new element, maintaining the max length. Do() accepts a function, and iterates forward performing that function on each element in the ring.

Movement

Moving around the ring is achieved by calling Next(), Prev(), or Move(n) where n is an integer. Positive integers Move forward, negative integers Move backwards around the ring. All movement methods return the destination value.

Values

Calling Value() on any ring element provides the value of the current cursor position within the ring. Calling SetValue() on any ring element replaces the value at the current cursor position.

Example

package main

import (
  "fmt"
  "bytes"
  
  "fifo"
)

func printRing(r *fifo.Ring) {
  var buf bytes.Buffer
  fmt.Fprint(&buf, "{ ")
  r.Do(func(p interface{}) {
		fmt.Fprintf(&buf, "%d ", p.(int))
	})
    fmt.Fprintf(&buf, "} Len: %d, Avail: %d", r.Len(), r.Avail())
  fmt.Println(buf.String())
}

func main() {
  max := 5
  r := fifo.NewRing(max)
  printRing(r)
  for i := 0; i < (max * 2); i++ {
    r.Push(i)
    printRing(r)
  }
  _ = r.Pop()
  printRing(r)
}

Results in:

{ } Len: 0, Avail: 5
{ 0 } Len: 1, Avail: 4
{ 0 1 } Len: 2, Avail: 3
{ 0 1 2 } Len: 3, Avail: 2
{ 0 1 2 3 } Len: 4, Avail: 1
{ 0 1 2 3 4 } Len: 5, Avail: 0
{ 1 2 3 4 5 } Len: 5, Avail: 0
{ 2 3 4 5 6 } Len: 5, Avail: 0
{ 3 4 5 6 7 } Len: 5, Avail: 0
{ 4 5 6 7 8 } Len: 5, Avail: 0
{ 5 6 7 8 9 } Len: 5, Avail: 0
{ 6 7 8 9 } Len: 4, Avail: 1