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 int page = tx.allocator().alloc(1);
078 if (page == 0) {
079 // if we just created the file, first allocated page should be 0
080 ROOT_INDEXES_FACTORY.create(tx, 0);
081 LOG.info("Aggregation repository data store created using file: " + getFile());
082 } else {
083 // Was previously created.. so free up the test page
084 tx.allocator().free(page, 1);
085 SortedIndex<String, Integer> indexes = ROOT_INDEXES_FACTORY.open(tx, 0);
086 LOG.info("Aggregation repository data store loaded using file: " + getFile()
087 + " containing " + indexes.size() + " repositories.");
088 }
089 return true;
090 }
091 });
092 }
093
094 public void stop() {
095 if (LOG.isDebugEnabled()) {
096 LOG.debug("Stopping HawtDB using file: " + getFile());
097 }
098
099 close();
100 pageFile = null;
101 }
102
103 public <T> T execute(Work<T> work) {
104 if (LOG.isTraceEnabled()) {
105 LOG.trace("Executing work +++ start +++ " + work);
106 }
107
108 Transaction tx = pageFile.tx();
109 T answer = doExecute(work, tx, pageFile);
110
111 if (LOG.isTraceEnabled()) {
112 LOG.trace("Executing work +++ done +++ " + work);
113 }
114 return answer;
115 }
116
117 public SortedIndex<Buffer, Buffer> getRepositoryIndex(Transaction tx, String name, boolean create) {
118 SortedIndex<Buffer, Buffer> answer = null;
119
120 SortedIndex<String, Integer> indexes = ROOT_INDEXES_FACTORY.open(tx, 0);
121 Integer location = indexes.get(name);
122
123 if (create && location == null) {
124 // create it..
125 int page = tx.allocator().alloc(1);
126 SortedIndex<Buffer, Buffer> created = INDEX_FACTORY.create(tx, page);
127
128 // add it to indexes so we can find it the next time
129 indexes.put(name, page);
130
131 if (LOG.isDebugEnabled()) {
132 LOG.debug("Created new repository index with name " + name + " at location " + page);
133 }
134
135 answer = created;
136 } else if (location != null) {
137 if (LOG.isTraceEnabled()) {
138 LOG.trace("Repository index with name " + name + " at location " + location);
139 }
140 answer = INDEX_FACTORY.open(tx, location);
141 }
142
143 if (LOG.isTraceEnabled()) {
144 LOG.trace("Repository index with name " + name + " -> " + answer);
145 }
146 return answer;
147 }
148
149 private static <T> T doExecute(Work<T> work, Transaction tx, TxPageFile page) {
150 T answer = null;
151
152 boolean done = false;
153 int attempt = 0;
154 while (!done) {
155 try {
156 // only log at DEBUG level if we are retrying
157 if (attempt > 0 && LOG.isDebugEnabled()) {
158 LOG.debug("Attempt " + attempt + " to execute work " + work);
159 }
160 attempt++;
161
162 answer = work.execute(tx);
163 // commit work
164 tx.commit();
165 // and flush so we ensure data is spooled to disk
166 page.flush();
167 // and we are done
168 done = true;
169 } catch (OptimisticUpdateException e) {
170 // retry as we hit an optimistic update error
171 LOG.warn("OptimisticUpdateException occurred at attempt " + attempt + " executing work " + work + " will do rollback and retry.");
172 // no harm doing rollback before retry and no wait is needed
173 tx.rollback();
174 } catch (RuntimeException e) {
175 LOG.warn("Error executing work " + work + " will do rollback.", e);
176 tx.rollback();
177 throw e;
178 }
179 }
180
181 return answer;
182 }
183
184 }