Umh, sorry for a _really_ slow reply, apparently I lost or missed your mail somehow. I only re-found this bug now. Replying in hope that it is still useful :) And yes, the version number is a typo. > Did you profile any of these changes separately? What were the objective > results from your changes as a whole? I don't remember profiling those changes separately. The most objective results I got were callgrind (the Valgrind profiling tool) reporting less consumed cycles; the less objective results were aptitude running faster on my P100 (and under callgrind). All of the optimizations I did were to places pointed as bottlenecks by callgrind profiling and all of my optimizations did result in a speedup. >Integral_ mdz: yes, some of the idioms there are weird. I'd also think > that insert(s.end(), s2.begin(), s2.end()) should be the same as s > += s2. >Integral_ mdz: I think he changed += to push_back in some places > because he changed a string to a vector >Integral_ which seems pointless to me >Integral_ unless the g++ implementation of std::string is truly > atrocious Hmm. I seem to remember that appending to a string once did take time linear to both the strings, however this doesn't seem to be the case anymore. I wrote a small program (attached) to illustrate the effect of the changes I made to QuoteString. Here's some results on my computer: $ /usr/bin/time ./test_QuoteString 1.99user 0.00system 0:02.03elapsed 98%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+299minor)pagefaults 0swaps [change the program to use QuoteString_vec instead of QuoteString_str] $ /usr/bin/time ./test_QuoteString 1.39user 0.00system 0:01.49elapsed 93%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+299minor)pagefaults 0swaps So using a vector resulted in a 30% speedup. I also claim that QuoteString was a place where it made difference (or actually see the QuoteURI I made, an even more optimized version for URIs that makes more of a difference). Sami
#include <string>
#include <vector>
using namespace std;
string QuoteString_str(const string &Str, const char *Bad)
{
string Res;
for (string::const_iterator I = Str.begin(); I != Str.end(); I++)
{
if (strchr(Bad,*I) != 0 || isprint(*I) == 0 ||
*I <= 0x20 || *I >= 0x7F)
{
char Buf[10];
sprintf(Buf,"%%%02x",(int)*I);
Res += Buf;
}
else
Res += *I;
}
return Res;
}
string QuoteString_vec(const string &Str, const char *Bad)
{
vector<char> Res;
Res.reserve(Str.length()*3/2);
for (string::const_iterator I = Str.begin(); I != Str.end(); I++)
{
if (strchr(Bad,*I) != 0 || isprint(*I) == 0 ||
*I <= 0x20 || *I >= 0x7F)
{
char Buf[10];
sprintf(Buf,"%%%02x",(int)*I);
copy(Buf,Buf+3,back_insert_iterator<vector<char> >(Res));
}
else
Res.push_back(*I);
}
return string(Res.begin(),Res.end());
}
int main(void) {
for (int s=0; s<500000; s++) {
QuoteString_str("http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=319377";,
"\\|{}[]<>\"^~_=!@#$%^&*");
// QuoteString_vec("http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=319377";,
// "\\|{}[]<>\"^~_=!@#$%^&*");
}
}
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