Windows Command Line - Select Server Based upon Ping Latency - windows

Question

Ok basic premise here is that there are two servers with the same files.
I'm using Windows command line scripts and opening a network share to either of those hosts. I'd like to make the script "smart" so it works out the latency between the two servers and picks the lowest latency host to connect to.
I want to do something like (i know this code doesn't work, it's an example of my concept):
PING 192.168.0.1
SET HOST1=%ERRORLEVEL%
PING 192.168.0.2
SET HOST2=%ERRORLEVEL%
IF HOST1 GTR HOST2 GOTO HOST2CONNECT
:HOST1CONNECT
NET USE X: \\HOST1 (etc)
:HOST2CONNECT
NET USE X: \\HOST2 (etc)
Does that make any sense? I just can't seem to visualise a way of comparing the data from the two PING tests and i know that ERRORLEVEL in this situation is just a 1 or 0 based upon whether the ping is successful or not, so it's garbage as they'll both succeed. But i'm hoping you get the concept and can see what i'm missing.
Thanks in advance.

Answer 1

#echo off
setlocal enableextensions disabledelayedexpansion
rem Initialize variables
set "selected="
set "min=99999999"
set serverList= "bing.com" "duckduckgo.com" "google.es" "google.com"
echo - Testing -----------------------------
rem Enumerate the hosts to check
for %%a in ( %serverList% ) do (
rem Ping the host and retrieve the average roundtrip
for /f "tokens=6 delims== " %%r in ('
ping -n 1 "%%~a" ^| findstr /r /c:"^ .*ms$"
') do for /f "delims=ms" %%t in ("%%r") do (
echo "%%~a" : %%t ms
rem Determine if the current host has a lower rtt
rem if %%t geq min or min is already 0, then we have
rem a division by 0, else a lower rtt has been found
set /a "1/(min/(%%t+1))" && (
set "selected=%%~a"
set "min=%%t"
)
rem Of course this can be done with delayed expansion,
rem just a question of personal preferences
)
) 2>nul
echo(
echo - Selected ----------------------------
echo %selected% : %min%

Answer 2

MC ND posted his answer before I did so he should deserve the credits. Please do not mark this as the answer, that is not the intention of my post.
Because I had already made the effort of posting an answer as well and for sake of completeness, I feel that it doesn't hurt to post another approach to deal with the problem. The main difference is that I've chosen to use the average round-trip times of the ping command and provide a way to store the latency times and target host names in a group of variables that could be considered an array of structures.
Keep in mind that measuring round-trip latency with the ping command is not very accurate and the results can fluctuate tremendously. Referring to the following quote from Wikipedia:
Many software platforms provide a service called ping that can be used
to measure round-trip latency. Ping performs no packet processing; it
merely sends a response back when it receives a packet (i.e. performs
a no-op), thus it is a first rough way of measuring latency. Ping
cannot perform accurate measurements, principally because it uses the
ICMP protocol that is used only for diagnostic or control purposes,
and differs from real communication protocols such as TCP.
Furthermore, routers and ISP's might apply different traffic shaping
policies to different protocols.
#echo off
setlocal enabledelayedexpansion
set targets="192.168.0.1" "192.168.0.2"
for %%e in (%targets%) do (
call :GetAverageLatency %%e latency
if errorlevel 1 (
echo Unable to obtain latency from host: %%~e
exit /b
)
set /a count+=1
set "host[!count!].name=%%~e"
set "host[!count!].latency=!latency!"
if -!latency! gtr -!lowest! (
set lowest=!latency!
set index=!count!
)
)
echo;Mapping network drive to host: !host[%index%].name!
echo;
net use * "\\!host[%index%].name!"
set host
exit /b
:GetAverageLatency (__in hostName, __out *latency) {
for /f "skip=10 tokens=13 delims=m " %%e in ('ping "%~1"') do (
set "%2=%%e"
exit /b 0
)
exit /b 1
}
The set host command is obviously not necessary but it used to show the values stored in the host* variables.