org.rocksdb.NativeLibraryLoader Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of rocksdbjni Show documentation
RocksDB fat jar that contains .so files for linux32 and linux64 (glibc and musl-libc), jnilib files for Mac OSX, and a .dll for Windows x64.
The newest version!
// Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
package org.rocksdb;

import java.io.*;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;

import org.rocksdb.util.Environment;

/**
 * This class is used to load the RocksDB shared library from within the jar.
 * The shared library is extracted to a temp folder and loaded from there.
 */
public class NativeLibraryLoader {
  //singleton
  private static final NativeLibraryLoader instance = new NativeLibraryLoader();
  private static boolean initialized = false;

  private static final String ROCKSDB_LIBRARY_NAME = "rocksdb";

  private static final String sharedLibraryName =
      Environment.getSharedLibraryName(ROCKSDB_LIBRARY_NAME);
  private static final String jniLibraryName = Environment.getJniLibraryName(ROCKSDB_LIBRARY_NAME);
  private static final /* @Nullable */ String fallbackJniLibraryName =
      Environment.getFallbackJniLibraryName(ROCKSDB_LIBRARY_NAME);
  private static final String jniLibraryFileName =
      Environment.getJniLibraryFileName(ROCKSDB_LIBRARY_NAME);
  private static final /* @Nullable */ String fallbackJniLibraryFileName =
      Environment.getFallbackJniLibraryFileName(ROCKSDB_LIBRARY_NAME);
  private static final String tempFilePrefix = "librocksdbjni";
  private static final String tempFileSuffix = Environment.getJniLibraryExtension();

  /**
   * Get a reference to the NativeLibraryLoader
   *
   * @return The NativeLibraryLoader
   */
  public static NativeLibraryLoader getInstance() {
    return instance;
  }

  /**
   * Firstly attempts to load the library from java.library.path,
   * if that fails then it falls back to extracting
   * the library from the classpath
   * {@link org.rocksdb.NativeLibraryLoader#loadLibraryFromJar(java.lang.String)}
   *
   * @param tmpDir A temporary directory to use
   *   to copy the native library to when loading from the classpath.
   *   If null, or the empty string, we rely on Java's
   *   {@link java.io.File#createTempFile(String, String)}
   *   function to provide a temporary location.
   *   The temporary file will be registered for deletion
   *   on exit.
   *
   * @throws java.io.IOException if a filesystem operation fails.
   */
  @SuppressWarnings("PMD.EmptyCatchBlock")
  public synchronized void loadLibrary(final String tmpDir) throws IOException {
    try {
      // try dynamic library
      System.loadLibrary(sharedLibraryName);
      return;
    } catch (final UnsatisfiedLinkError ule) {
      // ignore - try from static library
    }

    try {
      // try static library
      System.loadLibrary(jniLibraryName);
      return;
    } catch (final UnsatisfiedLinkError ule) {
      // ignore - then try static library fallback or from jar
    }

    if (fallbackJniLibraryName != null) {
      try {
        // try static library fallback
        System.loadLibrary(fallbackJniLibraryName);
        return;
      } catch (final UnsatisfiedLinkError ule) {
        // ignore - then try from jar
      }
    }

    // try jar
    loadLibraryFromJar(tmpDir);
  }

  /**
   * Attempts to extract the native RocksDB library
   * from the classpath and load it
   *
   * @param tmpDir A temporary directory to use
   *   to copy the native library to. If null,
   *   or the empty string, we rely on Java's
   *   {@link java.io.File#createTempFile(String, String)}
   *   function to provide a temporary location.
   *   The temporary file will be registered for deletion
   *   on exit.
   *
   * @throws java.io.IOException if a filesystem operation fails.
   */
  void loadLibraryFromJar(final String tmpDir)
      throws IOException {
    if (!initialized) {
      System.load(loadLibraryFromJarToTemp(tmpDir).getAbsolutePath());
      initialized = true;
    }
  }

  private File createTemp(final String tmpDir, final String libraryFileName) throws IOException {
    // create a temporary file to copy the library to
    final File temp;
    if (tmpDir == null || tmpDir.isEmpty()) {
      temp = File.createTempFile(tempFilePrefix, tempFileSuffix);
    } else {
      final File parentDir = new File(tmpDir);
      if (!parentDir.exists()) {
        throw new RuntimeException(
            "Directory: " + parentDir.getAbsolutePath() + " does not exist!");
      }
      temp = new File(parentDir, libraryFileName);
      if (temp.exists() && !temp.delete()) {
        throw new RuntimeException(
            "File: " + temp.getAbsolutePath() + " already exists and cannot be removed.");
      }
      if (!temp.createNewFile()) {
        throw new RuntimeException("File: " + temp.getAbsolutePath() + " could not be created.");
      }
    }
    if (temp.exists()) {
      temp.deleteOnExit();
      return temp;
    } else {
      throw new RuntimeException("File " + temp.getAbsolutePath() + " does not exist.");
    }
  }

  @SuppressWarnings({"PMD.UseProperClassLoader", "PMD.UseTryWithResources"})
  File loadLibraryFromJarToTemp(final String tmpDir) throws IOException {
    try (InputStream is = getClass().getClassLoader().getResourceAsStream(jniLibraryFileName)) {
      if (is != null) {
        final File temp = createTemp(tmpDir, jniLibraryFileName);
        Files.copy(is, temp.toPath(), StandardCopyOption.REPLACE_EXISTING);
        return temp;
      }
    }

    if (fallbackJniLibraryFileName == null) {
      throw new RuntimeException(fallbackJniLibraryFileName + " was not found inside JAR.");
    }

    try (InputStream is =
             getClass().getClassLoader().getResourceAsStream(fallbackJniLibraryFileName)) {
      if (is != null) {
        final File temp = createTemp(tmpDir, fallbackJniLibraryFileName);
        Files.copy(is, temp.toPath(), StandardCopyOption.REPLACE_EXISTING);
        return temp;
      }
    }

    throw new RuntimeException(jniLibraryFileName + " was not found inside JAR.");
  }

  /**
   * Private constructor to disallow instantiation
   */
  private NativeLibraryLoader() {
  }
}