001 /**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.camel.component.hawtdb;
018
019 import org.apache.camel.Service;
020 import org.apache.commons.logging.Log;
021 import org.apache.commons.logging.LogFactory;
022 import org.fusesource.hawtbuf.Buffer;
023 import org.fusesource.hawtbuf.codec.BufferCodec;
024 import org.fusesource.hawtbuf.codec.IntegerCodec;
025 import org.fusesource.hawtbuf.codec.StringCodec;
026 import org.fusesource.hawtdb.api.BTreeIndexFactory;
027 import org.fusesource.hawtdb.api.OptimisticUpdateException;
028 import org.fusesource.hawtdb.api.SortedIndex;
029 import org.fusesource.hawtdb.api.Transaction;
030 import org.fusesource.hawtdb.api.TxPageFile;
031 import org.fusesource.hawtdb.api.TxPageFileFactory;
032
033 /**
034 * Manages access to a shared <a href="http://hawtdb.fusesource.org/">HawtDB</a> file.
035 * <p/>
036 * Will by default not sync writes which allows it to be faster.
037 * You can force syncing by setting the sync option to <tt>true</tt>.
038 */
039 public class HawtDBFile extends TxPageFileFactory implements Service {
040
041 private static final transient Log LOG = LogFactory.getLog(HawtDBFile.class);
042
043 // the root which contains an index with name -> page for the real indexes
044 private static final BTreeIndexFactory<String, Integer> ROOT_INDEXES_FACTORY = new BTreeIndexFactory<String, Integer>();
045 // the real indexes where we store persisted data in buffers
046 private static final BTreeIndexFactory<Buffer, Buffer> INDEX_FACTORY = new BTreeIndexFactory<Buffer, Buffer>();
047
048 private TxPageFile pageFile;
049
050 static {
051 ROOT_INDEXES_FACTORY.setKeyCodec(StringCodec.INSTANCE);
052 ROOT_INDEXES_FACTORY.setValueCodec(IntegerCodec.INSTANCE);
053 ROOT_INDEXES_FACTORY.setDeferredEncoding(true);
054 INDEX_FACTORY.setKeyCodec(BufferCodec.INSTANCE);
055 INDEX_FACTORY.setValueCodec(BufferCodec.INSTANCE);
056 INDEX_FACTORY.setDeferredEncoding(true);
057 }
058
059 public HawtDBFile() {
060 setSync(false);
061 }
062
063 public void start() {
064 if (getFile() == null) {
065 throw new IllegalArgumentException("A file must be configured");
066 }
067
068 if (LOG.isDebugEnabled()) {
069 LOG.debug("Starting HawtDB using file: " + getFile());
070 }
071
072 open();
073 pageFile = getTxPageFile();
074
075 execute(new Work<Boolean>() {
076 public Boolean execute(Transaction tx) {
077 if (!tx.allocator().isAllocated(0)) {
078 // if we just created the file, first allocated page should be 0
079 ROOT_INDEXES_FACTORY.create(tx);
080 LOG.info("Aggregation repository data store created using file: " + getFile());
081 } else {
082 SortedIndex<String, Integer> indexes = ROOT_INDEXES_FACTORY.open(tx);
083 LOG.info("Aggregation repository data store loaded using file: " + getFile()
084 + " containing " + indexes.size() + " repositories.");
085 }
086 return true;
087 }
088
089 @Override
090 public String toString() {
091 return "Allocation repository file: " + getFile();
092 }
093 });
094 }
095
096 public void stop() {
097 if (LOG.isDebugEnabled()) {
098 LOG.debug("Stopping HawtDB using file: " + getFile());
099 }
100
101 close();
102 pageFile = null;
103 }
104
105 public <T> T execute(Work<T> work) {
106 if (LOG.isTraceEnabled()) {
107 LOG.trace("Executing work +++ start +++ " + work);
108 }
109
110 Transaction tx = pageFile.tx();
111 T answer = doExecute(work, tx, pageFile);
112
113 if (LOG.isTraceEnabled()) {
114 LOG.trace("Executing work +++ done +++ " + work);
115 }
116 return answer;
117 }
118
119 public SortedIndex<Buffer, Buffer> getRepositoryIndex(Transaction tx, String name, boolean create) {
120 SortedIndex<Buffer, Buffer> answer = null;
121
122 SortedIndex<String, Integer> indexes = ROOT_INDEXES_FACTORY.open(tx);
123 Integer location = indexes.get(name);
124
125 if (create && location == null) {
126 // create it..
127 SortedIndex<Buffer, Buffer> created = INDEX_FACTORY.create(tx);
128 int page = created.getIndexLocation();
129
130 // add it to indexes so we can find it the next time
131 indexes.put(name, page);
132
133 if (LOG.isDebugEnabled()) {
134 LOG.debug("Created new repository index with name " + name + " at location " + page);
135 }
136
137 answer = created;
138 } else if (location != null) {
139 if (LOG.isTraceEnabled()) {
140 LOG.trace("Repository index with name " + name + " at location " + location);
141 }
142 answer = INDEX_FACTORY.open(tx, location);
143 }
144
145 if (LOG.isTraceEnabled()) {
146 LOG.trace("Repository index with name " + name + " -> " + answer);
147 }
148 return answer;
149 }
150
151 private static <T> T doExecute(Work<T> work, Transaction tx, TxPageFile page) {
152 T answer = null;
153
154 boolean done = false;
155 int attempt = 0;
156 while (!done) {
157 try {
158 // only log at DEBUG level if we are retrying
159 if (attempt > 0 && LOG.isDebugEnabled()) {
160 LOG.debug("Attempt " + attempt + " to execute work " + work);
161 }
162 attempt++;
163
164 // execute and get answer
165 answer = work.execute(tx);
166
167 if (LOG.isTraceEnabled()) {
168 LOG.trace("TX is read only: " + tx.isReadOnly() + " for executed work: " + work);
169 }
170 // commit work
171 tx.commit();
172 // and flush so we ensure data is spooled to disk
173 page.flush();
174 // and we are done
175 done = true;
176 } catch (OptimisticUpdateException e) {
177 // retry as we hit an optimistic update error
178 LOG.warn("OptimisticUpdateException occurred at attempt " + attempt + " executing work " + work + ". Will do rollback and retry.");
179 // no harm doing rollback before retry and no wait is needed
180 tx.rollback();
181 } catch (RuntimeException e) {
182 LOG.warn("Error executing work " + work + ". Will do rollback.", e);
183 tx.rollback();
184 throw e;
185 }
186 }
187
188 return answer;
189 }
190
191 }