/**
   * Initializes store.
   *
   * @throws GridException If failed to initialize.
   */
  private void init() throws GridException {
    if (initGuard.compareAndSet(false, true)) {
      if (log.isDebugEnabled()) log.debug("Initializing cache store.");

      try {
        if (sesFactory != null)
          // Session factory has been provided - nothing to do.
          return;

        if (!F.isEmpty(hibernateCfgPath)) {
          try {
            URL url = new URL(hibernateCfgPath);

            sesFactory = new Configuration().configure(url).buildSessionFactory();

            if (log.isDebugEnabled()) log.debug("Configured session factory using URL: " + url);

            // Session factory has been successfully initialized.
            return;
          } catch (MalformedURLException e) {
            if (log.isDebugEnabled())
              log.debug("Caught malformed URL exception: " + e.getMessage());
          }

          // Provided path is not a valid URL. File?
          File cfgFile = new File(hibernateCfgPath);

          if (cfgFile.exists()) {
            sesFactory = new Configuration().configure(cfgFile).buildSessionFactory();

            if (log.isDebugEnabled())
              log.debug("Configured session factory using file: " + hibernateCfgPath);

            // Session factory has been successfully initialized.
            return;
          }

          // Provided path is not a file. Classpath resource?
          sesFactory = new Configuration().configure(hibernateCfgPath).buildSessionFactory();

          if (log.isDebugEnabled())
            log.debug("Configured session factory using classpath resource: " + hibernateCfgPath);
        } else {
          if (hibernateProps == null) {
            U.warn(
                log, "No Hibernate configuration has been provided for store (will use default).");

            hibernateProps = new Properties();

            hibernateProps.setProperty("hibernate.connection.url", DFLT_CONN_URL);
            hibernateProps.setProperty("hibernate.show_sql", DFLT_SHOW_SQL);
            hibernateProps.setProperty("hibernate.hbm2ddl.auto", DFLT_HBM2DDL_AUTO);
          }

          Configuration cfg = new Configuration();

          cfg.setProperties(hibernateProps);

          assert resourceAvailable(MAPPING_RESOURCE);

          cfg.addResource(MAPPING_RESOURCE);

          sesFactory = cfg.buildSessionFactory();

          if (log.isDebugEnabled())
            log.debug("Configured session factory using properties: " + hibernateProps);
        }
      } catch (HibernateException e) {
        throw new GridException("Failed to initialize store.", e);
      } finally {
        initLatch.countDown();
      }
    } else if (initLatch.getCount() > 0) U.await(initLatch);

    if (sesFactory == null) throw new GridException("Cache store was not properly initialized.");
  }
    /** @param workTokDir Token directory (common for multiple nodes). */
    private void processTokenDirectory(File workTokDir) {
      for (File f : workTokDir.listFiles()) {
        if (!f.isDirectory()) {
          if (!f.getName().equals(LOCK_FILE_NAME)) {
            if (log.isDebugEnabled()) log.debug("Unexpected file: " + f.getName());
          }

          continue;
        }

        if (f.equals(tokDir)) {
          if (log.isDebugEnabled()) log.debug("Skipping own token directory: " + tokDir.getName());

          continue;
        }

        String name = f.getName();

        int pid;

        try {
          pid = Integer.parseInt(name.substring(name.lastIndexOf('-') + 1));
        } catch (NumberFormatException ignored) {
          if (log.isDebugEnabled()) log.debug("Failed to parse file name: " + name);

          continue;
        }

        // Is process alive?
        if (IpcSharedMemoryUtils.alive(pid)) {
          if (log.isDebugEnabled()) log.debug("Skipping alive node: " + pid);

          continue;
        }

        if (log.isDebugEnabled()) log.debug("Possibly stale token folder: " + f);

        // Process each token under stale token folder.
        File[] shmemToks = f.listFiles();

        if (shmemToks == null)
          // Although this is strange, but is reproducible sometimes on linux.
          return;

        int rmvCnt = 0;

        try {
          for (File f0 : shmemToks) {
            if (log.isDebugEnabled()) log.debug("Processing token file: " + f0.getName());

            if (f0.isDirectory()) {
              if (log.isDebugEnabled()) log.debug("Unexpected directory: " + f0.getName());
            }

            // Token file format: gg-shmem-space-[auto_idx]-[other_party_pid]-[size]
            String[] toks = f0.getName().split("-");

            if (toks.length != 6) {
              if (log.isDebugEnabled()) log.debug("Unrecognized token file: " + f0.getName());

              continue;
            }

            int pid0;
            int size;

            try {
              pid0 = Integer.parseInt(toks[4]);
              size = Integer.parseInt(toks[5]);
            } catch (NumberFormatException ignored) {
              if (log.isDebugEnabled()) log.debug("Failed to parse file name: " + name);

              continue;
            }

            if (IpcSharedMemoryUtils.alive(pid0)) {
              if (log.isDebugEnabled()) log.debug("Skipping alive process: " + pid0);

              continue;
            }

            if (log.isDebugEnabled()) log.debug("Possibly stale token file: " + f0);

            IpcSharedMemoryUtils.freeSystemResources(f0.getAbsolutePath(), size);

            if (f0.delete()) {
              if (log.isDebugEnabled()) log.debug("Deleted file: " + f0.getName());

              rmvCnt++;
            } else if (!f0.exists()) {
              if (log.isDebugEnabled())
                log.debug("File has been concurrently deleted: " + f0.getName());

              rmvCnt++;
            } else if (log.isDebugEnabled()) log.debug("Failed to delete file: " + f0.getName());
          }
        } finally {
          // Assuming that no new files can appear, since
          if (rmvCnt == shmemToks.length) {
            U.delete(f);

            if (log.isDebugEnabled()) log.debug("Deleted empty token directory: " + f.getName());
          }
        }
      }
    }