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 org.apache.jackrabbit.oak.spi.blob; import java.io.ByteArrayOutputStream; 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.security.DigestInputStream; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.util.Iterator; import java.util.List; import javax.annotation.Nullable; import com.google.common.base.Predicate; import com.google.common.collect.AbstractIterator; import com.google.common.collect.FluentIterable; import com.google.common.io.Files; import org.apache.commons.io.FileUtils; import org.apache.commons.io.FilenameUtils; import org.apache.jackrabbit.oak.commons.IOUtils; import org.apache.jackrabbit.oak.commons.StringUtils; /** * A file blob store. */ public class FileBlobStore extends AbstractBlobStore { private static final String OLD_SUFFIX = "_old"; private static final String FILE_SUFFIX = ".dat"; private final File baseDir; private final byte[] buffer = new byte[16 * 1024]; private boolean mark; // TODO file operations are not secure (return values not checked, no retry,...) public FileBlobStore(String dir) { baseDir = new File(dir); baseDir.mkdirs(); } @Override public String writeBlob(String tempFilePath) throws IOException { File file = new File(tempFilePath); InputStream in = new FileInputStream(file); MessageDigest messageDigest; try { messageDigest = MessageDigest.getInstance(HASH_ALGORITHM); } catch (NoSuchAlgorithmException e) { throw new IOException(e); } DigestInputStream din = new DigestInputStream(in, messageDigest); long length = file.length(); try { while (true) { int len = din.read(buffer, 0, buffer.length); if (len < 0) { break; } } } finally { din.close(); } ByteArrayOutputStream idStream = new ByteArrayOutputStream(); idStream.write(TYPE_HASH); IOUtils.writeVarInt(idStream, 0); IOUtils.writeVarLong(idStream, length); byte[] digest = messageDigest.digest(); File f = getFile(digest, false); if (f.exists()) { file.delete(); } else { File parent = f.getParentFile(); if (!parent.exists()) { parent.mkdirs(); } file.renameTo(f); } IOUtils.writeVarInt(idStream, digest.length); idStream.write(digest); byte[] id = idStream.toByteArray(); String blobId = StringUtils.convertBytesToHex(id); usesBlobId(blobId); return blobId; } @Override protected synchronized void storeBlock(byte[] digest, int level, byte[] data) throws IOException { File f = getFile(digest, false); if (f.exists()) { return; } File parent = f.getParentFile(); if (!parent.exists()) { parent.mkdirs(); } File temp = new File(parent, f.getName() + ".temp"); OutputStream out = new FileOutputStream(temp, false); out.write(data); out.close(); temp.renameTo(f); } private File getFile(byte[] digest, boolean old) { String id = StringUtils.convertBytesToHex(digest); String sub1 = id.substring(id.length() - 2); String sub2 = id.substring(id.length() - 4, id.length() - 2); if (old) { sub2 += OLD_SUFFIX; } return new File(new File(new File(baseDir, sub1), sub2), id + FILE_SUFFIX); } @Override protected byte[] readBlockFromBackend(BlockId id) throws IOException { File f = getFile(id.digest, false); if (!f.exists()) { File old = getFile(id.digest, true); f.getParentFile().mkdir(); old.renameTo(f); f = getFile(id.digest, false); } int length = (int) Math.min(f.length(), getBlockSize()); byte[] data = new byte[length]; InputStream in = new FileInputStream(f); try { IOUtils.skipFully(in, id.pos); IOUtils.readFully(in, data, 0, length); } finally { in.close(); } return data; } @Override public void startMark() throws IOException { mark = true; for (int j = 0; j < 256; j++) { String sub1 = StringUtils.convertBytesToHex(new byte[] { (byte) j }); File x = new File(baseDir, sub1); for (int i = 0; i < 256; i++) { String sub2 = StringUtils.convertBytesToHex(new byte[] { (byte) i }); File d = new File(x, sub2); File old = new File(x, sub2 + OLD_SUFFIX); if (d.exists()) { if (old.exists()) { for (File p : d.listFiles()) { String name = p.getName(); File newName = new File(old, name); p.renameTo(newName); } } else { d.renameTo(old); } } } } markInUse(); } @Override protected boolean isMarkEnabled() { return mark; } @Override protected void mark(BlockId id) throws IOException { File f = getFile(id.digest, false); if (!f.exists()) { File old = getFile(id.digest, true); f.getParentFile().mkdir(); old.renameTo(f); f = getFile(id.digest, false); } } @Override public int sweep() throws IOException { int count = 0; for (int j = 0; j < 256; j++) { String sub1 = StringUtils.convertBytesToHex(new byte[] { (byte) j }); File x = new File(baseDir, sub1); for (int i = 0; i < 256; i++) { String sub = StringUtils.convertBytesToHex(new byte[] { (byte) i }); File old = new File(x, sub + OLD_SUFFIX); if (old.exists()) { for (File p : old.listFiles()) { String name = p.getName(); File file = new File(old, name); file.delete(); count++; } old.delete(); } } } mark = false; return count; } @Override public long countDeleteChunks(List<String> chunkIds, long maxLastModifiedTime) throws Exception { int count = 0; for (String chunkId : chunkIds) { byte[] digest = StringUtils.convertHexToBytes(chunkId); File f = getFile(digest, false); if (!f.exists()) { File old = getFile(digest, true); f.getParentFile().mkdir(); old.renameTo(f); f = getFile(digest, false); } if ((maxLastModifiedTime <= 0) || FileUtils.isFileOlder(f, maxLastModifiedTime)) { f.delete(); count++; } } return count; } @Override public Iterator<String> getAllChunkIds(final long maxLastModifiedTime) throws Exception { FluentIterable<File> iterable = Files.fileTreeTraverser().postOrderTraversal(baseDir); final Iterator<File> iter = iterable.filter(new Predicate<File>() { // Ignore the directories and files newer than maxLastModifiedTime if specified @Override public boolean apply(@Nullable File input) { if (!input.isDirectory() && ((maxLastModifiedTime <= 0) || FileUtils.isFileOlder(input, maxLastModifiedTime))) { return true; } return false; } }).iterator(); return new AbstractIterator<String>() { @Override protected String computeNext() { if (iter.hasNext()) { File file = iter.next(); return FilenameUtils.removeExtension(file.getName()); } return endOfData(); } }; } @Override public void clearCache() { // no cache } }