RWBench

Module:  Essential Tools Module   Group:  Miscellaneous Classes

Does not inherit

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Members

doLoop() duration() go() idleLoop() innerLoops()

machine() ops() opsRate() outerLoops() parse()

report() RWBench() setDuration() setInnerLoops() time()

what() where()

#include <rw/bench.h>
(Abstract base class)

This is an abstract class that can automate the process of benchmarking a piece of code. To use it, derive a class from RWBench, including a definition for the virtual function doLoop(unsigned long N). This function should perform N operations of the type that you are trying to benchmark. RWBench will call doLoop() over and over again until a preset amount of time has elapsed. It will then sum the total number of operations performed.

To run, construct an instance of your derived class and then call go(). Then call report() to get a standard summary. For many compilers, this summary will automatically include the compiler type and memory model. You can call ops(), outerLoops(), etc. for more detail.

If you wish to correct for overhead, then provide an idleLoop() function which should do all non-benchmark-related calculations.

None

This example compares string parsing operations by benchmarking a brute force approach versus using RWCString.

#include <cstdlib>
#include <iostream>

#include <rw/bench.h>    /* Benchmark software */
#include <rw/cstring.h>  /* Rogue Wave string class */

#include <rw/ctoken.h>
#include <rw/regexp.h>

// The string to be hashed:
static const char* g_string = 
"A multi-character string with lots of words "
"in it to be parsed out and searched for.";

struct TestBrute : public RWBench 
{
    TestBrute() { }

    virtual void doLoop(unsigned long);

    virtual void idleLoop(unsigned long);

    virtual void what (std::ostream& s) const { 
        s << "Brute force string search: \n"; 
    }
};

struct TestRW : public RWBench 
{
public:

    TestRW() { }

    virtual void doLoop(unsigned long);

    virtual void idleLoop(unsigned long);

    virtual void what (std::ostream& s) const { 
        s << "Rogue Wave search: \n"; 
    }
};

/*****************************************************/

void TestBrute::doLoop(unsigned long n)
{
    RWCString s (g_string);
    RWCTokenizer *tokener;
    RWCString token;

    tokener = new RWCTokenizer(s);

    while (n--) {
 
        if((token = (*tokener)()).isNull()) {
            delete tokener;
            tokener = new RWCTokenizer (s);
            token = (*tokener)();
        }

        size_t j = 0;

        for(size_t i = 0; i < s.length() && j != token.length(); ++i) 
            for (j = 0; (j < token.length ()) && (s [i + j] == token [j]); ++j) { 
            }
    }
    delete tokener;
}

void TestRW::doLoop (unsigned long n)
{
    RWCString s(g_string);
    RWCTokenizer *tokener;
    RWCString token, result;
    RWCRegexp re("");

    tokener = new RWCTokenizer(s);
 
    while(n--) {
 
        if((token = (*tokener)()).isNull()) {
            delete tokener;
            tokener = new RWCTokenizer(s);
            token = (*tokener)();
        } 

        re = RWCRegexp(token); 
        result = s(re); // Do the search! 
    }
    delete tokener;
}

void TestBrute::idleLoop(unsigned long n)
{
    // Subtract the overhead
    RWCString s(g_string); 
    RWCTokenizer *tokener;
    RWCString token;

    tokener = new RWCTokenizer(s);
 
    while(n--) {
 
        if((token = (*tokener)()).isNull()) {
            delete tokener;
            tokener = new RWCTokenizer(s);
            token = (*tokener)();
        } 
    }
    delete tokener;
}

void TestRW::idleLoop(unsigned long n)
{
    RWCString s(g_string); // Subtract out the overhead
    RWCTokenizer *tokener;
    RWCString token, result;
    RWCRegexp re("");

    tokener = new RWCTokenizer(s);
 
    while(n--){
         if((token = (*tokener)()).isNull()) {
            delete tokener;
            tokener = new RWCTokenizer(s);
            token = (*tokener)();
        } 
        re = RWCRegexp(token); 
    }
    delete tokener;
}

/*****************************************************/

int main (int argc, char** argv)
{
    std::cout << "Testing string \"" << g_string << "\".\n";

    // Test brute force string search algorithm:
    TestBrute other;
    other.parse(argc, argv);
    other.go();
    other.report(std::cout);

    // Test RW searching w/regular expressions:
    TestRW rw;
    rw.parse(argc, argv);
    rw.go();
    rw.report(std::cout);

    return 0;
}

Program Output:

Testing string
A multi-character string with lots of words in it to be parsed out and searched for.
Microsoft C/C++
 
Brute force string search:
 
Iterations:                 60
Inner loop operations:      1000
Total operations:           60000
Elapsed (user) time:        4.39632
Kilo-operations per second: 13.6478
 
Microsoft C/C++
 
Rogue Wave search:
 
Iterations:                 138
Inner loop operations:      1000
Total operations:           138000
Elapsed (user) time:        2.11304
Kilo-operations per second: 65.3088

RWBench(double duration = 5, unsigned long ILO=1000,
        const char* machine = 0);

The parameter duration is the nominal amount of time that the benchmark should take in seconds. The virtual function doLoop(unsigned long) is called over and over again until at least this amount of time has elapsed. The parameter ILO is the number of "inner loop operations" that should be performed. This parameter is passed in as parameter N to doLoop(N). Parameter machine is an optional null terminated string that should describe the test environment (perhaps the hardware the benchmark is being run on).

virtual void
doLoop(unsigned long N)=0;

A pure virtual function whose actual definition should be supplied by the specializing class. This function will be repeatedly called until a time duration has elapsed. It should perform the operation to be benchmarked N times. See the example.

double
duration() const;

Return the current setting for the benchmark test duration. This should not be confused with function time() which returns the actual test time.

virtual void
go();

Call this function to run the benchmark.

virtual void
idleLoop(unsigned long N);

This function can help to correct the benchmark for overhead. The default definition merely executes a "for()" loop N times. See the example.

const char *
machine();

This function accesses the name of the machine which is passed into the benchmark object through parse().

virtual void
parse(int argc, char* argv[]);

This function allows an easy way to change the test duration, number of inner loops and machine description from the command line.

Table 12: Parse arguments

Argument	Type	Description
argv[1]	double	Duration (sec.)
argv[2]	unsigned long	No. of inner loops
argv[3]	const char*	Machine

void
parse(const char *);

This is a non-virtual function which provides the same service as parse(int argc, char * argv[]), but is designed for Windows users. It extracts tokens from the null-terminated command argument provided by Windows, then calls the virtual parse for ANSI C command arguments.

virtual void
report(std::ostream&) const;

Calling this function provides an easy and convenient way of getting an overall summary of the results of a benchmark.

double
setDuration(double t);

Change the test duration to time t.

unsigned long
setInnerLoops(unsigned long N);

Change the number of "inner loop operations" to N.

virtual void
what(std::ostream&) const;

You can supply a specializing version of this virtual function that provides some detail of what is being benchmarked. It is called by report() when generating a standard report.

void
where(std::ostream&) const;

This function will print information to the stream about the compiler and memory model that the code was compiled under.

unsigned long
innerLoops() const;

Returns the current setting for the number of inner loop operations that will be passed into function doLoop(unsigned long N) as parameter N.

double
time() const;

Returns the amount of time the benchmark took, corrected for overhead.

unsigned long
outerLoops() const;

Returns the number of times the function doLoop() was called.

double
ops() const;

Returns the total number of inner loop operations that were performed (the product of the number of times outerLoop() was called times the number of inner loop operations performed per call).

double
opsRate() const;

Returns the number of inner loop operations per second.

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