From 09e24cda650d44725b4f9f2d5739618221396472 Mon Sep 17 00:00:00 2001
From: "Sascha L. Teichmann" <sascha.teichmann@intevation.de>
Date: Tue, 10 Mar 2015 12:08:14 +0100
Subject: [PATCH] Optimize the case that nothing has changes concerning the
 players. This should not lead to broadcasting of notifications.

---
 cmd/mtwebmapper/players.go | 46 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 44 insertions(+), 2 deletions(-)

diff --git a/cmd/mtwebmapper/players.go b/cmd/mtwebmapper/players.go
index 483c6e6..11f0b2a 100644
--- a/cmd/mtwebmapper/players.go
+++ b/cmd/mtwebmapper/players.go
@@ -6,8 +6,10 @@ import (
 	"encoding/json"
 	"html/template"
 	"log"
+	"math"
 	"net/http"
 	"os"
+	"sort"
 	"sync"
 	"time"
 )
@@ -51,6 +53,27 @@ func (p *player) MarshalJSON() ([]byte, error) {
 	return buf.Bytes(), nil
 }
 
+func (p *player) same(o *player) bool {
+	return p.Name == o.Name &&
+		math.Abs(p.X-o.X) < 0.000001 &&
+		math.Abs(p.Y-o.Y) < 0.000001 &&
+		math.Abs(p.Z-o.Z) < 0.000001
+}
+
+type sortPlayersByName []*player
+
+func (pls sortPlayersByName) Len() int {
+	return len(pls)
+}
+
+func (pls sortPlayersByName) Less(i, j int) bool {
+	return pls[i].Name < pls[j].Name
+}
+
+func (pls sortPlayersByName) Swap(i, j int) {
+	pls[i], pls[j] = pls[j], pls[i]
+}
+
 func (ps *players) readFromFIFO() ([]*player, error) {
 	file, err := os.Open(ps.fifo)
 	if err != nil {
@@ -67,6 +90,18 @@ func (ps *players) readFromFIFO() ([]*player, error) {
 	return pls, nil
 }
 
+func differentPlayers(a, b []*player) bool {
+	if len(a) == len(b) {
+		return true
+	}
+	for i, p := range a {
+		if !p.same(b[i]) {
+			return true
+		}
+	}
+	return false
+}
+
 func (ps *players) run() {
 	for {
 		pls, err := ps.readFromFIFO()
@@ -74,10 +109,17 @@ func (ps *players) run() {
 			time.Sleep(sleepInterval)
 			continue
 		}
+		if pls == nil {
+			continue
+		}
+		sort.Sort(sortPlayersByName(pls))
+		var change bool
 		ps.mu.Lock()
-		ps.pls = pls
+		if change = differentPlayers(pls, ps.pls); change {
+			ps.pls = pls
+		}
 		ps.mu.Unlock()
-		if ps.wsf != nil {
+		if change && ps.wsf != nil {
 			// TODO: Throttle this!
 			ps.wsf.BroadcastPlayers(pls)
 		}