116 lines
3.9 KiB
JavaScript
116 lines
3.9 KiB
JavaScript
/*
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HTML5 Speedtest v4.7 MPOT - Server selector
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by Federico Dossena
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https://github.com/adolfintel/speedtest/
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GNU LGPLv3 License
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*/
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//pings the specified URL, then calls the function result. Result will receive a parameter which is either the time it took to ping the URL, or -1 if something went wrong.
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var PING_TIMEOUT=1000;
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var USE_PING_TIMEOUT=true; //will be disabled on unsupported browsers
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if(/MSIE.(\d+\.\d+)/i.test(navigator.userAgent)){ //IE11 doesn't support XHR timeout
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USE_PING_TIMEOUT=false;
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}
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function ping(url,result){
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var xhr=new XMLHttpRequest();
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var t=new Date().getTime();
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xhr.onload=function(){
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if(xhr.responseText.length==0){ //we expect an empty response
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var instspd=new Date().getTime()-t; //rough timing estimate
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try{
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//try to get more accurate timing using performance API
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var p=performance.getEntries();
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p=p[p.length-1];
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var d=p.responseStart-p.requestStart;
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if(d<=0) d=p.duration;
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if(d>0&&d<instspd) instspd=d;
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}catch(e){
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}
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result(instspd);
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}else result(-1);
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}.bind(this);
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xhr.onerror=function(){
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result(-1);
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}.bind(this);
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xhr.open("GET",url);
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if(USE_PING_TIMEOUT){
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try{
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xhr.timeout=PING_TIMEOUT;
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xhr.ontimeout=xhr.onerror;
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}catch(e){}
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}
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xhr.send();
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}
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//this function repeatedly pings a server to get a good estimate of the ping. When it's done, it calls the done function without parameters. At the end of the execution, the server will have a new parameter called pingT, which is either the best ping we got from the server or -1 if something went wrong.
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var PINGS=3, //up to 3 pings are performed, unless the server is down...
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SLOW_THRESHOLD=500; //...or one of the pings is above this threshold
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function checkServer(server,done){
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var i=0;
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server.pingT=-1;
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if(server.server.indexOf(location.protocol)==-1) done(); else{
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var nextPing=function(){
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if(i++==PINGS){done(); return;}
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ping(server.server+server.pingURL,function(t){
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if(t>=0){
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if(t<server.pingT||server.pingT==-1) server.pingT=t;
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if(t<SLOW_THRESHOLD) nextPing(); else done();
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}else done();
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}.bind(this));
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}.bind(this);
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nextPing();
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}
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}
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/*this function goes through a list of servers, each with this format:
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{
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name: "User friendly name",
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server:"http://yourBackend.com/", <---- make sure there's a / at the end!
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dlURL:"garbage.php" <----- path to garbage.php or its replacement on the server
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ulURL:"empty.php" <----- path to empty.php or its replacement on the server
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pingURL:"empty.php" <----- path to empty.php or its replacement on the server. This is used to ping the server by this selector
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getIpURL:"getIP.php" <----- path to getIP.php or its replacement on the server
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}
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For each server, the ping is measured, then the server with the function result is called with the best server, or null if all the servers were down.
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*/
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function selectServer(serverList,result){
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var i=0;
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var done=function(){
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var bestServer=null;
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for(var i=0;i<serverList.length;i++){
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if(serverList[i].pingT!=-1&&(bestServer==null||serverList[i].pingT<bestServer.pingT)) bestServer=serverList[i];
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}
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result(bestServer);
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}.bind(this);
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var nextServer=function(){
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if(i==serverList.length){done(); return;}
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checkServer(serverList[i++],nextServer);
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}.bind(this);
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nextServer();
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}
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/*
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this function is a faster version of selectServer that tests multiple servers concurrently. Useful for large server lists
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*/
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var CONCURRENCY=4; //4 seems to be the safest value
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function fastSelectServer(serverList,result){
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var serverLists=[];
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for(var i=0;i<CONCURRENCY;i++){
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serverLists[i]=[];
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}
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for(var i=0;i<serverList.length;i++){
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serverLists[i%CONCURRENCY].push(serverList[i]);
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}
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var completed=0;
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var bestServer=null;
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for(var i=0;i<CONCURRENCY;i++){
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selectServer(serverLists[i],function(server){
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if(server!=null){
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if(bestServer==null||server.pingT<bestServer.pingT) bestServer=server;
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}
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completed++;
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if(completed==CONCURRENCY) result(bestServer);
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}.bind(this));
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}
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}
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