Exécution simultanée de plusieurs instances de l'application Netbeans RCP

Question

Nous avons une application basée sur la plateforme client riche Netbeans.

Le comportement par défaut est que seule une instance du logiciel peut être exécutée. Vous pouvez la remplacer en spécifiant un autre répertoire utilisateur en tant qu'argument lors du démarrage de l'application.

Existe-t-il des alternatives à cela? Nos clients comptent sur l’exécution de plusieurs instances de l’application.

(Nous préférerions que nous n'ayons pas à implémenter notre propre programme de lancement qui examine les répertoires netbeans pour les verrous afin qu'ils transmettent des userdirs alternatifs.

Existe-t-il une méthode intégrée dans le RCP de Netbeans pour prendre en charge facilement plusieurs instances?

acclamations / B

Answer 1

Donc, incapable de trouver un moyen approprié de le faire (il semble que ce sera disponible avec nb 7 via un nouveau paramètre d'entrée du lanceur), mon collègue l'a implémenté d'une manière quelque peu fictive.

Il a créé une classe principale alternative, qui vérifie et manipule la propriété user-dir afin que chaque instance obtienne son propre userdir.

Je suis toujours surpris que Netbeans n’ait pas cette fonctionnalité!

import java.io.File;

import org.netbeans.Main;

/**
 * Launches Netbeans Rich Client Platform application where mulitple instances of 
 * the application can run simultaneously for the same user.
 * <p>
 * Netbeans does not allow to run several instances of an application for the same 
 * user simultaneously, but this class does the job by fooling Netbeans.
 * If an instance is already running then a new folder is created and used for this instance.
 * </p>
 * <p>
 * This is quite tricky and this class is indeed a hack to override Netbeans behaviour.
 * An example makes it a little easier to understand, when application is first started 
 * Netbeans userdir is set from a configuration file like {@code etc/xxxxx.conf} to something like:<br>
 * {@code /home/username/.xxxxx/dev/} which includes a lock file.
 * <br>
 * If application is started again then this lock file is checked and Netbeans tries to connect to the other instance through a socket.
 * This class does the trick by never using this folder but instead creating unique directories for each instance like:<br>
 * {@code /home/username/.xxxxx/instance_01/netbeans/}<br>
 * {@code /home/username/.xxxxx/instance_02/netbeans/}<br>
 * {@code /home/username/.xxxxx/instance_03/netbeans/}<br>
 * ...
 * </p>
 * 
 */
public class MultipleInstancesMain
{
    /** Key for Netbeans default user dir */
    private static final String NETBEANS_USER = "netbeans.user";

    /** Argument to Netbeans for alternate user dir */
    private static final String USERDIR_ARG = "--userdir";

    /** Like "C:\Documents and Settings\username\Application Data\.xxxxx" or "/home/username/.xxxxx" */
    private static final File MAIN_DIR = getMainDir();

    /** Sub dir of MAIN_DIR for each instance of application */
    private static final String INSTANCE_DIR = "instance";

    /** Sub dir of INSTANCE_DIR where netbeans stores it's settings, logs and cache */
    private static final String NETBEANS_SUBDIR = "netbeans";

    /** Name of Netbeans lock file inside of NETBEANS_SUBDIR */
    private static final String LOCKFILE = "lock";

    /** Max number of instance directories we allow */
    private static final int MAX_DIR_COUNT = 999;

    /** Padding of instance dir */
    private static final String PAD = "000";
    private static final int PAD_LENGTH = PAD.length();

    /** 
     * Lock file could be present even though application is not running (after crash).
     * So we treat it as "dead" after some time, to prevent "dead directories".
     */
    private static final long LOCKFILE_MAX_AGE_IN_MILLIS = 1000L * 60L * 60L * 24L * 30L; // 30 days

    /**
     * Launches application with multiple instances support.
     * @param args command line arguments
     */
    public static void main(String[] args) throws Exception
    {
        // Get directory for this instance
        String[] userDir = new String[2];
        userDir[0] = USERDIR_ARG;
        userDir[1] = getNetbeansDir();

        // Remove default dir and set this class not to run again
        deleteDefaultNetbeansDir();
        System.clearProperty("netbeans.mainclass");

        // Start Netbeans again with new userdir and default main class
        startNetbeans(args, userDir);
    }

    /**
     * Starts Netbeans.
     * @param oldArgs command line arguments
     * @param newArgs new arguments added
     */
    private static void startNetbeans(String[] oldArgs, String[] newArgs)  throws Exception
    {
        String[] args = new String[oldArgs.length + newArgs.length];

        for (int i = 0; i <oldArgs.length; i++)
        {
            args[i] = oldArgs[i];
        }

        for (int i = 0; i < newArgs.length; i++)
        {
            args[oldArgs.length + i] = newArgs[i];
        }

        Main.main(args);
    }

    /**
     * @return the directory that Netbeans will use for this instance of the application 
     */
    private static String getNetbeansDir()
    {
        for(int i = 1; i <= MAX_DIR_COUNT; i++)
        {
            File instanceDir = getSuffixedInstanceDir(i);
            if (isLockFileFree(instanceDir))
            {
                File dirToUse = new File(instanceDir, NETBEANS_SUBDIR);
                return dirToUse.getAbsolutePath();
            }
        }

        // This would probably never happen, but we don't want an eternal loop above
        String errorMessage = String.format("Unable to find Netbeans userdir, %s dirs checked in '%s'", 
                MAX_DIR_COUNT, MAIN_DIR.getAbsolutePath());
        throw new RuntimeException(errorMessage);
    }

    private static File getSuffixedInstanceDir(int count)
    {
        String suffix = PAD + count;
        suffix = suffix.substring(suffix.length() - PAD_LENGTH);
        File suffixedDir = new File(MAIN_DIR, INSTANCE_DIR + "_" + suffix);
        return suffixedDir;
    }

    /**
     * Checks is if Netbeans lock file is free.
     * @param instanceDir directory to look for Netbeans directory and lock file in 
     * @return true if {@code instanceDir} does not have a Netbeans folder with a occupied lock file
     */
    private static boolean isLockFileFree(File instanceDir)
    {
        File netbeansDir = new File(instanceDir, NETBEANS_SUBDIR);
        File lockFile = new File(netbeansDir, LOCKFILE);

        if (lockFile.exists())
        {
            return deleteLockFileIfOldEnough(lockFile);
        }
        else
        {
            return true;
        }
    }

    /**
     * Deletes the lock file if it's old enough.
     * @param lockFile lock file to delete
     * @return true if it was deleted
     * @see #LOCKFILE_MAX_AGE_IN_MILLIS
     */
    private static boolean deleteLockFileIfOldEnough(File lockFile)
    {
        long currentTime = System.currentTimeMillis();
        long fileCreated = lockFile.lastModified();
        long ageInMillis = currentTime - fileCreated;

        if (ageInMillis > LOCKFILE_MAX_AGE_IN_MILLIS)
        {
            return lockFile.delete();
        }
        else
        {
            return false;
        }
    }

    /**
     * Netbeans is started with a default userdir, but we need to have a unique dir for each instance.
     * Main dir is the directory where directories of all instances are.
     * @return main directory in users home area where application settings, logs and cache is stored
     */
    private static File getMainDir()
    {
        String defaultNetbeansDir = System.getProperty(NETBEANS_USER);
        File mainDir = new File(defaultNetbeansDir).getParentFile();
        return mainDir;
    }

    /**
     * Since we don't use default Netbeans dir at all, we remove it completely.
     */
    private static void deleteDefaultNetbeansDir()
    {
        File defaultNetbeansDir = new File(System.getProperty(NETBEANS_USER));
        Thread t = new Thread(new DirectoryDeleter(defaultNetbeansDir), "NetbeansDirDeleter");
        t.start();
    }

    /**
     * There are unpredictable behaviour when deleting Netbeans default directory, sometime it succeeds and sometimes not.
     * But after some attempts it always succeeds, by deleting it in the background it will eventually be deleted.
     * @author username
     */
    private static class DirectoryDeleter implements Runnable
    {
        private static final long SLEEP_TIME = 3000;
        private final File dirToDelete;

        DirectoryDeleter(File dirToDelete)
        {
            this.dirToDelete = dirToDelete;
        }

        /**
         * @see java.lang.Runnable#run()
         */
        public void run()
        {
            while(!deleteDirOrFile(dirToDelete))
            {
                try
                {
                    Thread.sleep(SLEEP_TIME);
                }
                catch (InterruptedException e)
                {
                    // No idea to do anything here, should never happen anyway...
                    continue;
                }
            }
        }

        /**
         * Deletes a file or directory
         * @param dirFile directory or file to delete
         * @return true if deletion succeeded
         */
        private boolean deleteDirOrFile(File dirFile)
        {
            if (dirFile.isDirectory())
            {
                for (File f : dirFile.listFiles())
                {
                    boolean deleted = deleteDirOrFile(f);
                    if (!deleted)
                    {
                        return false;
                    }
                }
            }

            // The directory is now empty so delete it
            return dirFile.delete();
        }
    }
}

Answer 2

Je suis le développeur mystérieux qui a écrit la classe MultipleInstancesMain ci-dessus =)

.

En réponse aux questions de Swati Sharma et uvaraj ci-dessus, ces notes pourraient aider:

(1) La classe principale alternative ci-dessus devrait fonctionner pour les applications construites sur Netbeans Platform 6.5.1 (les nôtres), les autres versions que je ne connais pas.

(2) Nous conservons cette classe dans un petit projet construit par le script principal build.xml de notre application (celui du module "suite"). Le fichier jar est ensuite copié dans le dossier / [appname] / modules / (il est donc sur le chemin de classe Netbeans)

(3) Le projet séparé ne peut PAS être un module Netbeans, je suppose qu'il y aura une dépendance cyclique ou que le chargeur de classe Netbeans ne pourra pas le gérer ou quelque chose du genre.

(4) Notre application est ensuite démarrée en ajoutant un paramètre au fichier de configuration / [nomapplication] /etc/.conf :

default_options="-J-Dnetbeans.mainclass=com.appname.startup.MultipleInstancesMain"

J'espère que ça aide // Uhl & # 233; n