Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ package hivemall.xgboost; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.lang.reflect.Field; import java.util.UUID; import javax.annotation.Nonnull; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; public final class NativeLibLoader { private static final Log logger = LogFactory.getLog(NativeLibLoader.class); private static final String keyUserDefinedLib = "hivemall.xgboost.lib"; private static final String libPath = "/lib/"; private static boolean initialized = false; // Try to load a native library if it exists public static synchronized void initXGBoost() { if (!initialized) { // Since a user-defined native library has a top priority, // we first check if it is defined or not. final String userDefinedLib = System.getProperty(keyUserDefinedLib); if (userDefinedLib == null) { tryLoadNativeLibFromResource("xgboost4j"); } else { tryLoadNativeLib(userDefinedLib); } initialized = true; } } private static boolean hasResource(String path) { return NativeLibLoader.class.getResource(path) != null; } @Nonnull private static String getOSName() { return System.getProperty("os.name"); } private static void tryLoadNativeLibFromResource(final String libName) { // Resolve the library file name with a suffix (e.g., dll, .so, etc.) String resolvedLibName = System.mapLibraryName(libName); if (!hasResource(libPath + resolvedLibName)) { if (!getOSName().equals("Mac")) { return; } // Fix for openjdk7 for Mac // A detail of this workaround can be found in https://github.com/xerial/snappy-java/issues/6 resolvedLibName = "lib" + libName + ".jnilib"; if (hasResource(libPath + resolvedLibName)) { return; } } try { File tempFile = createTempFileFromResource(resolvedLibName, NativeLibLoader.class.getResourceAsStream(libPath + resolvedLibName)); logger.info("Copyed the native library in JAR as " + tempFile.getAbsolutePath()); addLibraryPath(tempFile.getParent()); } catch (Exception e) { // Simply ignore it here logger.info(e.getMessage()); } } private static void tryLoadNativeLib(final String userDefinedLib) { final File userDefinedLibFile = new File(userDefinedLib); if (!userDefinedLibFile.exists()) { logger.warn(userDefinedLib + " not found"); } else { try { File tempFile = createTempFileFromResource(userDefinedLibFile.getName(), new FileInputStream(userDefinedLibFile.getAbsolutePath())); logger.info("Copyed the user-defined native library as " + tempFile.getAbsolutePath()); addLibraryPath(tempFile.getParent()); } catch (Exception e) { // Simply ignore it here logger.warn(e.getMessage()); } } } @Nonnull private static String getPrefix(@Nonnull String fileName) { int point = fileName.lastIndexOf("."); if (point != -1) { return fileName.substring(0, point); } return fileName; } /** * Create a temp file that copies the resource from current JAR archive. * * @param libName Library name with a suffix * @param is Input stream to the native library * @return The created temp file * @throws IOException * @throws IllegalArgumentException */ static File createTempFileFromResource(String libName, InputStream is) throws IOException, IllegalArgumentException { // Create a temporary folder with a random number for the native lib final String uuid = UUID.randomUUID().toString(); final File tempFolder = new File(System.getProperty("java.io.tmpdir"), String.format("%s-%s", getPrefix(libName), uuid)); if (!tempFolder.exists()) { boolean created = tempFolder.mkdirs(); if (!created) { throw new IOException("Failed to create a temporary folder for the native lib"); } } // Prepare buffer for data copying final byte[] buffer = new byte[8192]; int readBytes; // Open output stream and copy the native library into the temporary one File extractedLibFile = new File(tempFolder.getAbsolutePath(), libName); final OutputStream os = new FileOutputStream(extractedLibFile); try { while ((readBytes = is.read(buffer)) != -1) { os.write(buffer, 0, readBytes); } } finally { // If read/write fails, close streams safely before throwing an exception os.close(); is.close(); } return extractedLibFile; } /** * Add libPath to java.library.path, then native library in libPath would be load properly. * * @param libPath library path * @throws IOException exception */ private static void addLibraryPath(String libPath) throws IOException { try { final Field field = ClassLoader.class.getDeclaredField("usr_paths"); field.setAccessible(true); final String[] paths = (String[]) field.get(null); for (String path : paths) { if (libPath.equals(path)) { return; } } final String[] tmp = new String[paths.length + 1]; System.arraycopy(paths, 0, tmp, 0, paths.length); tmp[paths.length] = libPath; field.set(null, tmp); } catch (IllegalAccessException e) { logger.error(e.getMessage()); throw new IOException("Failed to get permissions to set library path"); } catch (NoSuchFieldException e) { logger.error(e.getMessage()); throw new IOException("Failed to get field handle to set library path"); } } }