AttachOnce.java

/*
 *   libperfmap: a JVM agent to create perf-<pid>.map files for consumption
 *               with linux perf-tools
 *   Copyright (C) 2013-2015 Johannes Rudolph<johannes.rudolph@gmail.com>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License along
 *   with this program; if not, write to the Free Software Foundation, Inc.,
 *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

package net.virtualvoid.perf;

import java.io.File;

import com.sun.tools.attach.VirtualMachine;
import java.lang.management.ManagementFactory;

public class AttachOnce {
    public static void main(String[] args) throws Exception {
        String pid = args[0];
        String options = "";
        if (args.length > 1) options = args[1];
        loadAgent(pid, options);
    }

    static void loadAgent(String pid, String options) throws Exception {
        VirtualMachine vm = VirtualMachine.attach(pid);
        try {
            File lib = new File("libperfmap.so");
            String fullPath = lib.getAbsolutePath();
            if (!lib.exists()) {
                String [] javaLibPath = System.getProperty("java.library.path").split(":");
                boolean foundInLibPath = false;
                for (String path: javaLibPath) {
                    File f = new File(path + File.separator + "libperfmap.so");
                    if(f.exists()) {
                        foundInLibPath = true;
                        fullPath = f.getAbsolutePath();
                    }
                }
                if (!foundInLibPath) {
                    System.out.printf("Expected libperfmap.so at '%s' or within java.library.path but it didn't exist in either.\n", fullPath);
                    System.exit(1);
                }
            }
            vm.loadAgentPath(fullPath, options);
        } catch(com.sun.tools.attach.AgentInitializationException e) {
            // rethrow all but the expected exception
            if (!e.getMessage().equals("Agent_OnAttach failed")) throw e;
        } finally {
            vm.detach();
        }
    }
}