chope.go

// Package main provides a way to chope a place, once choped, other guys have
// to wait till it's available. chope is slang for reserved
package main

import (
	"fmt"
	"sync"
	"time"
)

const (
	waitLongLong int = iota
	putTissue
)

type choperer struct {
	Value string
	chope chan struct{}
}

func (c *choperer) canChope() (int, chan struct{}) {
	// Have not choped before
	if c.chope == nil {
		c.chope = make(chan struct{})
		return putTissue, c.chope
	}
	return waitLongLong, c.chope
}

func main() {
	// We got a table
	table := &choperer{}
	var wg sync.WaitGroup

	// 10 people want the stuff on the table
	wg.Add(10)
	for i := 0; i < 10; i++ {
		// Let all these people wait at the same time, and whoever is first get
		// to chope.
		go func(i int) {
			fmt.Printf("Customer %d trying to chope\n", i)
			chopeState, waitFirst := table.canChope()
			if chopeState == waitLongLong {
				<-waitFirst
			}

			if table.Value == "" {
				// 5 seconds is supposed makan time
				fmt.Printf("Customer %d got to chope first and eat\n", i)
				time.Sleep(2 * time.Second)
				table.Value = "Messy Table"
				close(waitFirst) // Done eating
			}
			fmt.Printf("%d left because of %s\n", i, table.Value)
			wg.Done()
		}(i)
	}
	wg.Wait() // Wait for program to finish
}

See it working in action -> http://play.golang.org/p/lo02RbuyMa