cxx-example.cpp

// Copyright (c) 2015-2022, Lawrence Livermore National Security, LLC.
// See top-level LICENSE file for details.

// A C++ Caliper instrumentation and ConfigManager example

//   Usage: $ cxx-example [-P <configuration-string>] <iterations>
// For example, "$ cxx-example -P runtime-report" will print a
// hierarchical runtime summary for all annotated regions.

#include <caliper/cali.h>
#include <caliper/cali-manager.h>

#include <time.h>

#include <cstring>
#include <iostream>
#include <string>

void print_help(const cali::ConfigManager& mgr)
{
    std::cerr << "Usage: cxx-example [-P caliper-config(arg=...,),...] [iterations]."
              << "\nAvailable configurations: ";

    auto configs = mgr.available_config_specs();

    // Print info on all available ConfigManager configurations.
    for (auto str : configs)
        std::cerr << "\n" << mgr.get_documentation_for_spec(str.c_str());

    std::cerr << std::endl;
}

double foo(int i)
{
    //   A function annotation. Opens region "function=foo" in Caliper,
    // and automatically closes it at the end of the function.
    CALI_CXX_MARK_FUNCTION;

    struct timespec sleeptime { 0, std::max<time_t>(i * 500, 100000) };
    nanosleep(&sleeptime, nullptr);

    return 0.5*i;
}

int main(int argc, char* argv[])
{
    //   The ConfigManager manages built-in or custom Caliper measurement
    // configurations, and provides an API to control performance profiling.
    cali::ConfigManager mgr;

    //   Parse command-line arguments. Let users choose a Caliper performance
    // profiling configuration via the "-P" command-line argument.
    std::string configstr;
    int iterations = 4;

    for (int a = 1; a < argc; ++a) {
        if (strcmp(argv[a], "-h") == 0 || strcmp(argv[a], "--help") == 0) {
            print_help(mgr);
            return 0;
        } else if (strcmp(argv[a], "-P") == 0) {
            ++a;
            if (argc > a)
                configstr = argv[a];
            else {
                std::cerr << "Expected config string after \"-P\"";
                return 1;
            }
        } else {
            try {
                iterations = std::stoi(argv[a]);
            } catch (std::invalid_argument) {
                std::cerr << "Invalid argument: \"" << argv[a]
                          << "\". Expected a number."
                          << std::endl;
                return 2;
            }
        }
    }

    //   Enable the requested performance measurement channels and start
    // profiling.
    mgr.add(configstr.c_str());

    if (mgr.error())
        std::cerr << "Caliper config error: " << mgr.error_msg() << std::endl;

    mgr.start();

    //   Add some run metadata information to be stored in the
    // performance profiles.
    cali_set_global_int_byname("iterations", iterations);
    cali_set_global_string_byname("caliper.config", configstr.c_str());

    //   Mark begin of the current function. Must be manually closed.
    // Opens region "function=main" in Caliper.
    CALI_MARK_FUNCTION_BEGIN;

    // Mark a code region. Opens region "annotation=init" in Caliper.
    CALI_MARK_BEGIN("init");
    double t = 0;
    CALI_MARK_END("init");

    // Mark a loop. Opens region "loop=mainloop" in Caliper.
    CALI_CXX_MARK_LOOP_BEGIN(loop_ann, "mainloop");

    for (int i = 0; i < iterations; ++i) {
        //   Mark loop iterations of an annotated loop.
        // Sets "iteration#main loop=<i> in Caliper.
        CALI_CXX_MARK_LOOP_ITERATION(loop_ann, i);

        //   A Caliper snapshot taken at this point will contain
        // { "function"="main", "loop"="mainloop", "iteration#main loop"=<i> }

        t += foo(i);
    }

    // Mark the end of the "loop=mainloop" region.
    CALI_CXX_MARK_LOOP_END(loop_ann);
    // Mark the end of the "function=main" region.
    CALI_MARK_FUNCTION_END;

    //   Trigger output in all Caliper control channels.
    // This should be done after all measurement regions have been closed.
    mgr.flush();
}