Re: [boost] [review] Boost.Guid

9 May 2007


      "Dave Jenkins" <david@jenkins.net> wrote in
news:f1t1qp$ra8$1@sea.gmane.org: 

< snip >
...
- What is your evaluation of the implementation?
I am concerned about the performance of this library when generating a
large number of GUIDs.  I wrote two small programs to compare
performance between MSVC 8.0 native mode using the Boost.GUID library
and C++.CLR using the Microsoft System.Guid library.  The CLR version
ran much faster.  For ten million GUIDs, the times were 5 seconds for
System.Guid, 16 seconds for Boost.GUID (random number based) and 12
seconds for Boost.Guid (name-based). The source code for the programs
is attached.  I would have expected the native mode program to run
faster or about the same.  Is there something wrong with my code?
Could this be caused by the Thread lock?  Or maybe the random number
generator takes more time?
First we aren't comparing the same thing.  System::Guid::NewGuid creates
a time-based guid and my library creates either a name-based or a
random-number-based guid.  But regardless, my library should be faster. 
I am sad that it is 2-3 times slower.  It does not seem to be the thread
lock.  Running your test with BOOST_DISABLE_THREADS shows little
improvement.  I have not profiled my code yet.  I assume that the random
number generator is slower than I would like, but I believe that I may
be using it inefficiently.  I will do my best to improve the speed.
...
- What is your evaluation of the documentation?
At the start of the document, I would prefer a text paragraph or two 
describing what a GUID is, what they look like, and what the library
does with them (input/output/create).  Also, a description of the
name-based and random-number-based alternatives might help up front. 
In the Design Notes section, could you provide a link to a SHA-1
reference like http://www.itl.nist.gov/fipspubs/fip180-1.htm.
Agreed.

< snip >
...
Regards,
Dave Jenkins
Attachment decoded: untitled-2.txt
------=_NextPart_000_003D_01C79241.6DA221A0
#include <boost/guid.hpp>
#include <boost/progress.hpp>
#include <string>
#include <vector>
int main(int, char*[])
{
    using namespace boost;
int const N = 10000000;
    std::vector<guid> g;
    g.reserve(N);
    guid dns_namespace_guid("6ba7b810-9dad-11d1-80b4-00c04fd430c8");
    timer t1;
    for (int i=0; i<N; i++)
        g.push_back(guid::create());
        //g.push_back(guid::create(dns_namespace_guid,
        "www.widgets.com", 15));
std::cout << "elapsed time: " << t1.elapsed() << '\n';
    std::cout << "count: " << N << '\n';
    return 0;
}
Attachment decoded: Test1.cpp
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// TestCLR.cpp : main project file.
using namespace System;
using namespace System::Collections::Generic;
int main(array<System::String ^> ^args)
{
    const int N = 10000000;
    List<Guid> ^g = gcnew List<Guid>();
    g->Capacity = N;
    DateTime t0 = DateTime::Now;
    for (int i = 0; i < N; i++)
        g->Add(Guid::NewGuid());
    TimeSpan ts = DateTime::Now - t0;
    Console::WriteLine("elapsed time=" + ts.ToString() +
        " Count="+g->Count.ToString());
    return 0;
}
Attachment decoded: TestCLR.cpp
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Andy.