JNA を使って Java から getrusage() を呼び出すサンプル

Main.java

package com.ynojima.utilization;

import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.Structure;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Main {
    public interface CLibrary extends Library {
        CLibrary INSTANCE = (CLibrary)Native.loadLibrary("c", CLibrary.class);

        int syscall(int number);
        int getrusage(int who, rusage usage);
    }

    public static class timeval extends Structure {
        public long tv_sec;
        public int tv_usec;

        @Override
        protected List getFieldOrder() {
            return Arrays.asList("tv_sec", "tv_usec");
        }

        @Override
        public String toString() {
            return String.format("%d.%06d", tv_sec, tv_usec);
        }
    }

    public static class rusage extends Structure {
        public timeval ru_utime;
        public timeval ru_stime;
        public long ru_maxrss;
        public long ru_ixrss;
        public long ru_idrss;
        public long ru_isrss;
        public long ru_minflt;
        public long ru_majflt;
        public long ru_nswap;
        public long ru_inblock;
        public long ru_oublock;
        public long ru_msgsnd;
        public long ru_msgrcv;
        public long ru_nsignals;
        public long ru_nvcsw;
        public long ru_nivcsw;

        @Override
        protected List getFieldOrder() {
            return Arrays.asList(
                "ru_utime",
                "ru_stime",
                "ru_maxrss",
                "ru_ixrss",
                "ru_idrss",
                "ru_isrss",
                "ru_minflt",
                "ru_majflt",
                "ru_nswap",
                "ru_inblock",
                "ru_oublock",
                "ru_msgsnd",
                "ru_msgrcv",
                "ru_nsignals",
                "ru_nvcsw",
                "ru_nivcsw");
        }
    }

    // wrapper function of gettid()
    private static int gettid() {
        final int SYS_gettid = 186;
        return CLibrary.INSTANCE.syscall(SYS_gettid);
    }

    // wrapper function of getrusage()
    private static rusage getrusage() {
        final int RUSAGE_THREAD = 1;
        rusage usage = new rusage();
        CLibrary.INSTANCE.getrusage(RUSAGE_THREAD, usage);
        return usage;
    }

    // --- 試しに動かしてみる ---

    private static class HelloRunnable implements Runnable {
        private final int index;

        HelloRunnable(int i) {
            index = i;
        }

        public void run() {
            long x = 0;
            for (long i = 0; i < 1000000000L * index; ++i) {
                x += i;
            }

            int tid = gettid();
            rusage usage = getrusage();

            System.err.println("[" + tid + "] ru_utime=" + usage.ru_utime + " ru_stime=" + usage.ru_stime + " x=" + x);
        }
    }

    public static void main(String[] args) throws Exception {
        List<Thread> threads = new ArrayList<>();
        for (int i = 0; i < 10; ++i)
            threads.add(new Thread(new HelloRunnable(i)));
        for (Thread t : threads)
            t.start();
        for (Thread t : threads)
            t.join();
    }
}