// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package net

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

func BenchmarkTCPOneShot(b *testing.B) {
	benchmarkTCP(b, false, false)
}

func BenchmarkTCPOneShotTimeout(b *testing.B) {
	benchmarkTCP(b, false, true)
}

func BenchmarkTCPPersistent(b *testing.B) {
	benchmarkTCP(b, true, false)
}

func BenchmarkTCPPersistentTimeout(b *testing.B) {
	benchmarkTCP(b, true, true)
}

func benchmarkTCP(b *testing.B, persistent, timeout bool) {
	const msgLen = 512
	conns := b.N
	numConcurrent := runtime.GOMAXPROCS(-1) * 16
	msgs := 1
	if persistent {
		conns = numConcurrent
		msgs = b.N / conns
		if msgs == 0 {
			msgs = 1
		}
		if conns > b.N {
			conns = b.N
		}
	}
	sendMsg := func(c Conn, buf []byte) bool {
		n, err := c.Write(buf)
		if n != len(buf) || err != nil {
			b.Logf("Write failed: %v", err)
			return false
		}
		return true
	}
	recvMsg := func(c Conn, buf []byte) bool {
		for read := 0; read != len(buf); {
			n, err := c.Read(buf)
			read += n
			if err != nil {
				b.Logf("Read failed: %v", err)
				return false
			}
		}
		return true
	}
	ln, err := Listen("tcp", "127.0.0.1:0")
	if err != nil {
		b.Fatalf("Listen failed: %v", err)
	}
	defer ln.Close()
	// Acceptor.
	go func() {
		for {
			c, err := ln.Accept()
			if err != nil {
				break
			}
			// Server connection.
			go func(c Conn) {
				defer c.Close()
				if timeout {
					c.SetDeadline(time.Now().Add(time.Hour)) // Not intended to fire.
				}
				var buf [msgLen]byte
				for m := 0; m < msgs; m++ {
					if !recvMsg(c, buf[:]) || !sendMsg(c, buf[:]) {
						break
					}
				}
			}(c)
		}
	}()
	sem := make(chan bool, numConcurrent)
	for i := 0; i < conns; i++ {
		sem <- true
		// Client connection.
		go func() {
			defer func() {
				<-sem
			}()
			c, err := Dial("tcp", ln.Addr().String())
			if err != nil {
				b.Logf("Dial failed: %v", err)
				return
			}
			defer c.Close()
			if timeout {
				c.SetDeadline(time.Now().Add(time.Hour)) // Not intended to fire.
			}
			var buf [msgLen]byte
			for m := 0; m < msgs; m++ {
				if !sendMsg(c, buf[:]) || !recvMsg(c, buf[:]) {
					break
				}
			}
		}()
	}
	for i := 0; i < cap(sem); i++ {
		sem <- true
	}
}