code: package io.ray.runtime.util;
  
  import com.google.common.collect.Sets;
  import com.sun.jna.NativeLibrary;
  import java.io.File;
  import java.io.IOException;
  import java.nio.file.Files;
  import java.util.Set;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  public class JniUtils {
    private static final Logger LOGGER = LoggerFactory.getLogger(JniUtils.class);
    private static Set<String> loadedLibs = Sets.newHashSet();
    private static String defaultDestDir;
  
    /**
     * Loads the native library specified by the <code>libraryName</code> argument. The <code>
     * libraryName</code> argument must not contain any platform specific prefix, file extension or
     * path.
     *
     * @param libraryName the name of the library.
     */
    public static synchronized void loadLibrary(String libraryName) {
      loadLibrary(getDefaultDestDir(), libraryName);
    }
  
    /**
     * Loads the native library specified by the <code>libraryName</code> argument. The <code>
     * libraryName</code> argument must not contain any platform specific prefix, file extension or
     * path.
     *
     * @param libraryName the name of the library.
     * @param exportSymbols export symbols of library so that it can be used by other libs.
     */
    public static synchronized void loadLibrary(String libraryName, boolean exportSymbols) {
      loadLibrary(getDefaultDestDir(), libraryName, exportSymbols);
    }
  
    /**
     * Loads the native library specified by the <code>libraryName</code> argument. The <code>
     * libraryName</code> argument must not contain any platform specific prefix, file extension or
     * path.
     *
     * @param destDir The destination dir the library to be extracted.
     * @param libraryName the name of the library.
     */
    public static synchronized void loadLibrary(String destDir, String libraryName) {
      loadLibrary(destDir, libraryName, false);
    }
  
    /**
     * Loads the native library specified by the <code>libraryName</code> argument. The <code>
     * libraryName</code> argument must not contain any platform specific prefix, file extension or
     * path.
     *
     * @param destDir The destination dir the library to be extracted.
     * @param libraryName the name of the library.
     * @param exportSymbols export symbols of library so that it can be used by other libs.
     */
    public static synchronized void loadLibrary(
        String destDir, String libraryName, boolean exportSymbols) {
      if (!loadedLibs.contains(libraryName)) {
        LOGGER.debug("Loading native library {} in {}.", libraryName, destDir);
        // Load native library.
        String fileName = System.mapLibraryName(libraryName);
        final File file = BinaryFileUtil.getNativeFile(destDir, fileName);
  
        if (exportSymbols) {
          // Expose library symbols using RTLD_GLOBAL which may be depended by other shared
          // libraries.
          NativeLibrary.getInstance(file.getAbsolutePath());
        }
        System.load(file.getAbsolutePath());
        LOGGER.debug("Native library loaded.");
        loadedLibs.add(libraryName);
      }
    }
  
    /** Cache the result so that multiple calls return the same dest dir. */
    private static synchronized String getDefaultDestDir() {
      if (defaultDestDir == null) {
        try {
          defaultDestDir = Files.createTempDirectory("native_libs").toString();
        } catch (IOException e) {
          throw new RuntimeException(e);
        }
      }
      return defaultDestDir;
    }
  }
  