idg/id.go

// idg is a go package that provides an entity that emits uniqueish identifiers.
package idg

import (
	"crypto/md5"
	"fmt"
	"io"
	"time"
)

// This thing contains a channel that when initialized (see NewGenerator)
// will return a bunch of (as best as I can tell) unique md5 hashes.
//
// we use this for naming players, games, etc.
//
// It will consume a single goroutine
type Generator struct {
	id chan int64
}

func NewGenerator() *Generator {
	return &Generator{
		id: make(chan int64),
	}
}

// Run is called (typically in a gorotine) to allow for queries to be made
// against Generator.id throgh the Hash method.
func (idg *Generator) Run() {
	var i int64
	for i = 0; ; i++ {
		idg.id <- i
	}
}

// Hash is the method used by a properly instantiated Generator that gives
// fairly unique strings. They are currently truncated md5 hashes of the time
// plus a unique counter
func (id *Generator) Hash() string {
	h := md5.New()
	ns := time.Now().UnixNano() + <-id.id
	io.WriteString(h, fmt.Sprintf("%d", ns))
	return fmt.Sprintf("%x", h.Sum(nil))[:8]
}