Java tutorial
/* * Data Hub Service (DHuS) - For Space data distribution. * Copyright (C) 2016 GAEL Systems * * This file is part of DHuS software sources. * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License as * published by the Free Software Foundation, either version 3 of the * License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ package fr.gael.dhus.util.http; import java.io.IOException; import java.nio.channels.FileChannel; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.nio.file.StandardCopyOption; import java.nio.file.StandardOpenOption; import java.security.MessageDigest; import java.util.Formatter; import java.util.concurrent.BlockingQueue; import java.util.concurrent.Callable; import java.util.concurrent.Future; import java.util.concurrent.LinkedBlockingDeque; import java.util.concurrent.ThreadFactory; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit; import java.util.regex.Matcher; import java.util.regex.Pattern; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.logging.log4j.LogManager; import org.apache.logging.log4j.Logger; /** * This class manages a pool of interruptible daemon threads which use instances of * {@link InterruptibleHttpClient} to download data. * * <p>Backed by a {@link ThreadPoolExecutor}, it creates only daemon threads and uses a unbounded * LinkedBlockingQueue to store tasks. * * <p>It will store the downloaded data in the current temp directory using * {@link Files#createTempFile(String, String, FileAttribute...)}. * * <p>If the HTTP Headers provided with the data contain a Filename field, this name will be used * to name the output file. */ public final class ParallelizedDownloadManager { /** Log. */ private static final Logger LOGGER = LogManager.getLogger(ParallelizedDownloadManager.class); private static final String TMP_FILE_SUFFIX = ".sync-data"; /** Thread pool. */ private final ThreadPoolExecutor threadPool; /** One HTTP client can be used by many concurrent threads. */ private final InterruptibleHttpClient http_client; /** Pattern for the filename property in the Content-Disposition HTTP Header field. */ private final Pattern pattern = Pattern.compile("filename=\"(.+?)\"", Pattern.CASE_INSENSITIVE); private final Path tempDir; /** * Creates a new Manager. * * @param core_pool_size the number of threads to keep in the pool, even if they are idle. * * @param max_pool_size the maximum number of threads to allow in the pool. * * @param keep_alive when the number of threads is greater than the core, this is the * maximum time that excess idle threads will wait for new tasks before * terminating. * * @param time_unit the time unit for the keepAliveTime argument. * * @param client_producer a custom http client provider to use custom http clients. * may be null. * * @param temp_dir base path for incomplete files (temporary directory). * may be null. */ public ParallelizedDownloadManager(int core_pool_size, int max_pool_size, long keep_alive, TimeUnit time_unit, HttpAsyncClientProducer client_producer, Path temp_dir) { BlockingQueue<Runnable> work_queue = new LinkedBlockingDeque<>(); this.threadPool = new ThreadPoolExecutor(core_pool_size, max_pool_size, keep_alive, time_unit, work_queue, new DaemonThreadFactory()); if (client_producer != null) { this.http_client = new InterruptibleHttpClient(client_producer); } else { this.http_client = new InterruptibleHttpClient(); } if (temp_dir != null) { if (!Files.isDirectory(temp_dir)) { throw new IllegalArgumentException("Given temp dir is not a dir"); } this.tempDir = temp_dir; } else { this.tempDir = null; } } /** * Calls `shutdownNow` on the {@link ThreadPoolExecutor} backing this manager. * @see ThreadPoolExecutor#shutdownNow() */ public void shutdownNow() { this.threadPool.shutdownNow(); } /** * The manager will create and add a download task to its task executor. * @param url_to_download url to download. * @return a Future holding a path to the downloaded data. */ public Future<DownloadResult> download(String url_to_download) { return this.threadPool.<DownloadResult>submit(new DownloadTask(url_to_download)); } /** Result type for {@link #download(String)}. */ public static class DownloadResult { /** Path to downloaded data. */ public final Path data; /** Content-Type of downloaded data. */ public final String dataType; /** Content-Length of downloaded data. */ public final long dataSize; /** MD5 sum of downloaded data. */ public final byte[] md5sum; /** * Create new instance, sets public fields. * @param data see {@link #data}. * @param dataType see {@link #dataType}. * @param dataSize see {@link #dataSize}. * @param md5sum see {@link #md5sum}. */ public DownloadResult(Path data, String dataType, long dataSize, byte[] md5sum) { this.data = data; this.dataType = dataType; this.dataSize = dataSize; this.md5sum = md5sum; } } // vvv Private classes vvv /** Download the given url, saves the data to a file */ private class DownloadTask implements Callable<DownloadResult> { private final String urlToDownload; /** Create a new DownloadTask with an URL to download. */ public DownloadTask(String url_to_download) { this.urlToDownload = url_to_download; } /** * In-thread code. * @return path to the downloaded data. */ @Override public DownloadResult call() throws Exception { Path out_file_path; if (tempDir != null) { out_file_path = Files.createTempFile(tempDir, null, TMP_FILE_SUFFIX); } else { out_file_path = Files.createTempFile(null, TMP_FILE_SUFFIX); } try (FileChannel output = FileChannel.open(out_file_path, StandardOpenOption.WRITE)) { // Computes the data's md5 sum on the fly MessageDigest md = MessageDigest.getInstance("MD5"); DigestIWC decorator = new DigestIWC(md, output); long delta = System.currentTimeMillis(); HttpResponse response = http_client.interruptibleGet(this.urlToDownload, decorator); LOGGER.debug(String.format("Downloaded '%s' in %d ms", this.urlToDownload, System.currentTimeMillis() - delta)); // If the response's status code is not 200, something wrong happened if (response.getStatusLine().getStatusCode() != HttpStatus.SC_OK) { Formatter ff = new Formatter(); ff.format("Cannot download from %s," + " remote host returned message '%s' (HTTP%d)", this.urlToDownload, response.getStatusLine().getReasonPhrase(), response.getStatusLine().getStatusCode()); throw new IOException(ff.out().toString()); } // Gets the filename from the HTTP header field `Content-Disposition' String contdis = response.getFirstHeader("Content-Disposition").getValue(); if (contdis != null && !contdis.isEmpty()) { Matcher m = pattern.matcher(contdis); if (m.find()) { String filename = m.group(1); if (filename != null && !filename.isEmpty()) { decorator.close(); // Renames the downloaded file Path rpath = Paths.get(filename); if (rpath.isAbsolute() || rpath.getNameCount() != 1) { String msg = String.format("invalid filename '%s' from %s", filename, this.urlToDownload); throw new IllegalStateException(msg); } Path dest = out_file_path.resolveSibling(rpath); Files.move(out_file_path, dest, StandardCopyOption.ATOMIC_MOVE); out_file_path = dest; } } } DownloadResult res = new DownloadResult(out_file_path, response.getEntity().getContentType().getValue(), response.getEntity().getContentLength(), md.digest()); return res; } catch (Exception e) { // cleanup if an error occured if (Files.exists(out_file_path)) { Files.delete(out_file_path); } throw e; } } } /** Creates only daemon threads. */ private class DaemonThreadFactory implements ThreadFactory { @Override public Thread newThread(Runnable r) { Thread thread = new Thread(r, "DownloadThread"); thread.setDaemon(true); return thread; } } }