// Testing code for concurrent buffer.
// This test generates long sequence of insertions, removals, and flushes
// in attempt to hit race condition

package lbuf

import (
	"testing"
	"fmt"
	"runtime"
	"time"
        )


// How many repetitions
var nrun int = 5
// How many elements inserted per test
var ninsert int = 1000
// How many elements removed
var nremove int = 1000
// How many flushes 
var nflush int = 1000

// Global variable to determine when removes completed
var rdone bool = false


// Concurrent testing

func rinsert(bp *Buf, dchan chan int, t *testing.T) {
	for inserted := 1; inserted <= ninsert; inserted++ {
		bp.Insert(inserted)
	}
	dchan <- 1
}

func rremove(bp *Buf, dchan chan int, t *testing.T) {
	for removed := 1; removed <= nremove; removed++ {
		bp.Remove()
	}
	rdone = true
	dchan <- 1
}

func rflush(bp *Buf, dchan chan int, t *testing.T) {
	for flushed := 1; flushed <= nflush; flushed++ {
		bp.Flush()
	}
	dchan <- 1
}


func TestRace(t *testing.T) {
	runtime.GOMAXPROCS(4)
	dchan := make(chan int, 2)
	rchan := make(chan int, 1)
	// Run same test nrun times
	for i := 0; i < nrun; i++ {
		bp := NewBuf()
		rdone = false
		go rinsert(bp, dchan, t)
		go rflush(bp, dchan, t)
		go rremove(bp, rchan, t)
		for j := 0; j < 2; j++ {
			<- dchan
		}
		// Let things run a while
		time.Sleep(3 * 1e9)
		var xinsert int
		for xinsert = 1; !rdone; xinsert++ {
			bp.Insert(0)
		}
		<- rchan
		fmt.Printf("Completed %d insertions, %d flushes, %d removals, %d extra insertions\n",
			ninsert, nflush, nremove, xinsert)
	}
	runtime.GOMAXPROCS(1)
}