outpipe.ipp

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#include <vector>
#include <array>
#include <iostream>
#include <sstream>
#include <ostream>
#include <string>
#include <cstdio>
 
namespace adc {
 
struct pipe_data {
    std::string output;
    int rc;
    friend std::ostream &operator<<(std::ostream &os, const pipe_data &pdata) {
        os << "proc rc: " << pdata.rc << " output: " << pdata.output;
        return os;
    }
    bool operator==(const pipe_data &rhs) const {
        return output == rhs.output &&
               rc == rhs.rc;
    }
    bool operator!=(const pipe_data &rhs) const {
        return !(rhs == *this);
    }
};
 
class out_pipe {
public:
    static pipe_data run(const std::string &proc) {
        int rc = 0;
        std::array<char, 8192> scratch {};
        std::string text;
        FILE *pipe = popen(proc.c_str(), "r");
        if (pipe == nullptr) {
            throw std::runtime_error("popen() fails: " + proc);
        }
        try {
            std::size_t inbytes;
            while ((inbytes = std::fread(scratch.data(), sizeof(scratch.at(0)), sizeof(scratch), pipe)) != 0) {
                text += std::string(scratch.data(), inbytes);
            }
        } catch (...) {
            pclose(pipe);
            throw;
        }
        int res = pclose(pipe);
        rc = WEXITSTATUS(res);
        return pipe_data{text, rc};
    }
 
};
 
} // end adc
 
#ifdef MAIN_out_pipe
int main() {
    pipe_data lscpu = out_pipe::run("lscpu -J");
    std::cout << lscpu.rc << std::endl;
    std::cout << lscpu.output << std::endl;
    return 0;
}
#endif
#ifdef MAIN_numactl
#if 0
available: 8 nodes (0-7)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 112 113 114 115 116 117 118 119 120 121 122 123 124 125
node 0 size: 31699 MB
node 0 free: 8914 MB
node distances:
#endif
 
int main() {
        static bool shell_done;
    int numa_json = -1;
        if (!shell_done) {
                size_t numa_node_count = 0;
        std::vector<std::string> sizes;
        std::vector<std::string> cpulist;
                shell_done = 1;
                pipe_data numactl = out_pipe::run("numactl -H");
                if (! numactl.rc) {
            std::string line;
            std::istringstream nss(numactl.output);
            while (std::getline(nss, line)) {
                size_t cp = line.find(':');
                std::string name = line.substr(0, cp);
                if (name == "available") {
                    std::istringstream iss(line.substr(cp+1));
                    iss >> numa_node_count;
                }
                if (name.substr(name.length()-4) == "cpus" ) {
                    cpulist.push_back(line.substr(cp+2));
                }
                if (name.substr(name.length()-4) == "size" ) {
                    sizes.push_back(line.substr(cp+2));
                }
                if (name.substr(name.length()-4) == "nces" )
                    break; // stop on "node distances:"
            }
            if (sizes.size() != numa_node_count || cpulist.size() != numa_node_count)
                return numa_json; // inconsistent data
            std::cout << numa_node_count << std::endl;
            for (size_t i = 0; i < numa_node_count; i++) {
                std::cout << sizes[i] <<std::endl;
                std::cout << cpulist[i] <<std::endl;
            }
                }
        }
        return numa_json;
}
#endif