util.go

package main

import (
	"log"
	"math/rand"
	"strings"
	"time"
)

//Call panic if err is not nil
func PanicIf(err error) {
	if err != nil {
		panic(err)
	}
}

//Prints error to stdout if err is not nil
func LogIf(err error, v ...string) {
	if err != nil {
		log.Println(strings.Join(v, ":"), err)
	}
}

//Emulates 5% probability
func prob() bool {
	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	n := r.Intn(100)
	return n <= 5
}

//Returns current mode
func Mode(g *Generator, c *Consumer) byte {
	if g.IsActive() {
		return MODE_GENERATOR
	}
	if c.IsActive() {
		return MODE_CONSUMER
	} else {
		return MODE_UNKNOWN
	}
}

//Pinger
//if mode = consumer try to acquire lock
//	if true stop consumer, start generator
//	if false start consumer
//
//if mode = generator try to acquire lock,
//	if false try to refresh lock
//	if false stop generator, run consumer
//
//if mode = unknown try to acquire lock
//	if true start generator
//	if false start consumer
func StartPing(g *Generator, c *Consumer) {
	ticker := time.NewTicker(time.Second * time.Duration(g.pingInterval))

	for range ticker.C {
		switch Mode(g, c) {
		case MODE_GENERATOR:
			if !g.AcquireLock() {
				switch g.RefreshLock() {
				case LOCK_NOT_REFRESHED:
					g.Stop()
					c.Start()
				}
			}
		case MODE_CONSUMER:
			if g.AcquireLock() {
				c.Stop()
				go g.Start()
			}
		case MODE_UNKNOWN:
			if g.AcquireLock() {
				go g.Start()
			} else {
				c.Start()
			}
		}
	}
}