On Saturday, 2 March 2013 at 01:05:35 UTC, cvk012c wrote:
On Saturday, 2 March 2013 at 00:47:02 UTC, Steven Schveighoffer
wrote:
On Fri, 01 Mar 2013 19:19:35 -0500, cvk012c
<[email protected]> wrote:
On Friday, 1 March 2013 at 21:52:13 UTC, bearophile wrote:
cvk012c:
I think that similar Perl and Java scripts will outperform
D easily.
Thanks Andrei and simendsjo for a quick response though.
Why don't you write a Java version? It takes only few
minutes, and you will have one more data point.
You are right. Why not. But instead of using Java split()
method I used combination of indexOf() and substring()
methods to do the same job. The reason: Java split method
implemented as a regular expression which will be unfair to
compare to D splitter. Again, I created a similar D version
of the script, compiled it with all suggested options:
-release -O -inline -noboundscheck and this time D version is
more then twice slower than Java: 8.4 seconds vs 4.
D experts, please, take a look at my code and tell me what is
wrong with it.
The issue is a combination of the fact that:
1. splitter is designed for any range, not just strings. Not
an excuse really, but a string-specific version could be
written that does better (clearly).
In my latest version of D script I didn't use splitter at all.
I used string specific indexOf function. Still result is very
bad. For text based protocols, such as SIP, performance of
string manipulating functions is very important. Unfortunately,
looks like it is not D strongest point at this time.
My version is functionally equivalent, and measures 55 - 94 ms
(depending on compiler; LDC is best). Your version performed in
about 7s on my machine.
Similar optimization taking advantage of immutability can be done
on your python translation that results in measurements of <1ms.
import std.stdio,std.string,std.datetime;
void main()
{
auto message = "REGISTER sip:example.com
SIP/2.0\r\nContent-Length: 0\r\nContact:
<sip:[email protected]:59788;transport=tls>;expires=4294967295;events=\"message-summary\";q=0.9\r\nTo:
<sip:[email protected]>\r\nUser-Agent: (\"VENDOR=MyCompany\"
\"My User Agent\")\r\nMax-Forwards: 70\r\nCSeq: 1
REGISTER\r\nVia: SIP/2.0/TLS
10.1.3.114:59788;branch=z9hG4bK2910497772630690\r\nCall-ID:
2910497622026445\r\nFrom:
<sip:[email protected]>;tag=2910497618150713\r\n\r\n";
auto t1 = Clock.currTime();
for (int i=0; i<10_000_000; i++)
{
while (true)
{
auto index = indexOf(message, "\r\n");
if (index == -1)
break;
auto notused = message[0..index];
message = message[index+2..$];
}
}
writeln(Clock.currTime()-t1);
}
