Java tutorial
/* * @(#)$Id$ * * Copyright 2006-2008 Makoto YUI * * Licensed 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. * * Contributors: * Makoto YUI - initial implementation */ package gridool.dht; import java.io.File; import java.util.ArrayList; import java.util.Collections; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Set; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import tokyocabinet.BDB; import tokyocabinet.BDBCUR; import gridool.GridNode; import gridool.communication.payload.GridNodeInfo; import gridool.locking.LockManager; import xbird.storage.DbCollection; import xbird.storage.DbException; import xbird.util.datetime.StopWatch; import xbird.util.string.StringUtils; /** * * <DIV lang="en"></DIV> * <DIV lang="ja"></DIV> * * @author Makoto YUI (yuin405@gmail.com) */ public final class TcbLocalDirectory extends AbstractLocalDirectory { private static final Log LOG = LogFactory.getLog(TcbLocalDirectory.class); private static final String DIR_IDX_NAME = "gridool.metaidx.tcb"; private final BDB tcb; public TcbLocalDirectory(LockManager lockManger) { super(lockManger); this.tcb = new BDB(); } public void start() throws DbException { DbCollection rootColl = DbCollection.getRootCollection(); File colDir = rootColl.getDirectory(); assert (colDir.exists()) : colDir.getAbsoluteFile(); File idxFile = new File(colDir, DIR_IDX_NAME); String filePath = idxFile.getAbsolutePath(); if (!tcb.open(filePath, (BDB.OWRITER | BDB.OCREAT))) { int ecode = tcb.ecode(); String errmsg = "open error: " + BDB.errmsg(ecode); LOG.fatal(errmsg); throw new DbException(errmsg); } else { LOG.info("Use a TokyoCabinet B+tree index on " + filePath + " for LocalDirectory"); } } public void close() throws DbException { if (!tcb.close()) { int ecode = tcb.ecode(); LOG.error("close error: " + BDB.errmsg(ecode)); } } public void addMapping(String[] keys, GridNodeInfo node) throws DbException { final byte[] value = node.toBytes(); for (String key : keys) { final byte[] kb = StringUtils.getBytes(key); if (!tcb.putdup(kb, value)) { int ecode = tcb.ecode(); String errmsg = "put failed: " + BDB.errmsg(ecode); LOG.error(errmsg); throw new DbException(errmsg); } } } @SuppressWarnings("unchecked") public List<GridNode> exactSearch(String key, List<GridNode> exclude) throws DbException { final byte[] kb = StringUtils.getBytes(key); final List<byte[]> results = tcb.getlist(kb); if (results == null) { return Collections.emptyList(); } final List<GridNode> nodes = new ArrayList<GridNode>(results.size()); for (byte[] v : results) { final GridNodeInfo node = GridNodeInfo.fromBytes(v); if (!exclude.contains(node)) { if (!nodes.contains(node)) { nodes.add(node); } } } return nodes; } @SuppressWarnings("unchecked") public Map<String, List<GridNode>> prefixSearch(String key, Set<GridNode> includeValues) throws DbException { final long startTime = System.currentTimeMillis(); final byte[] prefix = StringUtils.getBytes(key); final byte[] rightEdge = calculateRightEdgeValue(prefix); final List<byte[]> matchedKeys = tcb.range(prefix, true, rightEdge, false, -1); if (matchedKeys.isEmpty()) { return Collections.emptyMap(); } final Map<String, List<GridNode>> mapping = new HashMap<String, List<GridNode>>(matchedKeys.size()); int count = 0; for (byte[] k : matchedKeys) { final String path = StringUtils.toString(k); final List<byte[]> values = tcb.getlist(k); for (byte[] v : values) { count++; final GridNodeInfo node = GridNodeInfo.fromBytes(v); if (includeValues.contains(node)) { List<GridNode> nodes = mapping.get(path); if (nodes == null) { nodes = new ArrayList<GridNode>(32); mapping.put(path, nodes); } if (!nodes.contains(node)) { nodes.add(node); } } } } if (LOG.isInfoEnabled()) { long elapsedTime = System.currentTimeMillis() - startTime; LOG.info("Elapsed time for TcbLocalDirectory#prefixSearch with a '" + key + "' [ " + count + " items found. ] is " + StopWatch.elapsedTime(elapsedTime)); } return mapping; } private static final byte[] calculateRightEdgeValue(byte[] v) { final int vlen = v.length; final byte[] b = new byte[vlen + 1]; System.arraycopy(v, 0, b, 0, vlen); b[vlen] = Byte.MAX_VALUE; return b; } @SuppressWarnings("unchecked") public Map<String, List<GridNode>> prefixSearch2(String key, Set<GridNode> includeValues) throws DbException { final long startTime = System.currentTimeMillis(); final byte[] prefix = StringUtils.getBytes(key); final List<byte[]> results = tcb.fwmkeys(prefix, 1); if (results.isEmpty()) { return Collections.emptyMap(); } final Map<String, List<GridNode>> mapping = new HashMap<String, List<GridNode>>(128); final BDBCUR cursor = new BDBCUR(tcb); final byte[] firstMatchedKey = results.get(0); if (!cursor.jump(firstMatchedKey)) { throw new DbException("Could not jump. Illegal condition was detected for a key: " + key); } int count = 0; do { final byte[] k = cursor.key(); final byte[] v = cursor.val(); if (k == null || v == null) { if (LOG.isWarnEnabled()) { LOG.warn("Found illegal key '" + k + "' or value '" + v + '\''); } continue; } if (!startWith(k, prefix)) { break; } count++; final String path = StringUtils.toString(k); final GridNodeInfo node = GridNodeInfo.fromBytes(v); if (includeValues.contains(node)) {//TODO REVIEWME What's preferable behavior when all mapped node is down? List<GridNode> nodes = mapping.get(path); if (nodes == null) { nodes = new ArrayList<GridNode>(32); mapping.put(path, nodes); } if (!nodes.contains(node)) { nodes.add(node); } } } while (cursor.next()); if (LOG.isInfoEnabled()) { long elapsedTime = System.currentTimeMillis() - startTime; LOG.info("Elapsed time for TcbLocalDirectory#prefixSearch with a '" + key + "' [ " + count + " items found. ] is " + StopWatch.elapsedTime(elapsedTime)); } return mapping; } private static boolean startWith(final byte[] test, final byte[] prefix) { if (test.length < prefix.length) { return false; } for (int i = prefix.length - 1; i >= 0; i--) { if (test[i] != prefix[i]) { return false; } } return true; } }