berkeleydb的使用
在napoli的代码中发现这个berkeleydb，版本为3.2.43，使用代码如下
接口定义如下：
/**
* Project: napoli.client
*
* File Created at Sep 15, 2009
* $Id$
*
* Copyright 2008 Alibaba.com Croporation Limited.
* All rights reserved.
*
* This software is the confidential and proprietary information of
* Alibaba Company. ("Confidential Information"). You shall not
* disclose such Confidential Information and shall use it only in
* accordance with the terms of the license agreement you entered into
* with Alibaba.com.
*/
package com.alibaba.napoli.client.inner.persistencestore;
import java.io.Serializable;
import java.util.List;
import java.util.Map;
/**
* 持久化仓库的接口。
*
* @author ding.lid
* @author guolin.zhuanggl
*/
public interface PersistenceStore<T extends Serializable> {
/**
* 写入一条数据。会自动生成一个与之对应的key。
*
* @param data
*/
void write(T data);
/**
* 写入多条数据。
*
* @param dataList
*/
void batchWrite(List<T> dataList);
/**
* 读一条数据。<br>
* 如果读多条数据的情况下，尽量使用{@link #batchRead(int)}方法，有更好的效率。
*
* @return 读到的数据。如果store中没有数据，则返回<code>null</code>。
*/
Map.Entry<String, T> read();
/**
* 读多条数据。
*
* @param count 要读数据的条数
* @return 读到的数据。如果store中没有数据，则返回空的Map(即size ==0)。
*/
Map<String, T> batchRead(int count);
/**
* 删除一条数据。
*
* @param key
*/
void delete(String key);
/**
* 删除多条数据。
*
* @param keys 要删除数据的Key
*/
void delete(List<String> keys);
}
采用berkeleydb的实现如下：
/**
* Project: napoli.client
*
* File Created at Sep 15, 2009
* $Id$
*
* Copyright 2008 Alibaba.com Croporation Limited.
* All rights reserved.
*
* This software is the confidential and proprietary information of
* Alibaba Company. ("Confidential Information"). You shall not
* disclose such Confidential Information and shall use it only in
* accordance with the terms of the license agreement you entered into
* with Alibaba.com.
*/
package com.alibaba.napoli.client.inner.persistencestore.impl;
import java.io.File;
import java.io.Serializable;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.Map.Entry;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import com.alibaba.napoli.client.inner.persistencestore.PersistenceStore;
import com.sleepycat.bind.EntryBinding;
import com.sleepycat.bind.serial.SerialBinding;
import com.sleepycat.bind.serial.StoredClassCatalog;
import com.sleepycat.bind.tuple.TupleBinding;
import com.sleepycat.je.Cursor;
import com.sleepycat.je.Database;
import com.sleepycat.je.DatabaseConfig;
import com.sleepycat.je.DatabaseEntry;
import com.sleepycat.je.DatabaseException;
import com.sleepycat.je.Environment;
import com.sleepycat.je.EnvironmentConfig;
import com.sleepycat.je.EnvironmentMutableConfig;
import com.sleepycat.je.LockMode;
import com.sleepycat.je.OperationStatus;
import com.sleepycat.je.Transaction;
import com.sleepycat.je.TransactionConfig;
/**
* @author guolin.zhuanggl
* @author ding.lid
*/
public class BdbPersistenceStore<T extends Serializable> implements PersistenceStore<T> {
private static final Log log = LogFactory.getLog(BdbPersistenceStore.class);
private final static String MESSAGE_DBNAME = "MESSAGE_DB";
private final static String MESSAGE_CLASS_DBNAME = "MESSAGE_CLASS_DB";
private String bdbStorePath;
// 默认值 10M
private long bdbCheckpointBytes = 10 * 1024 * 1024;
// 默认值 5M
private long bdbCacheSize = 5 * 1024 * 1024;
private Environment bdbEnvironment;
private Database bdb;
private StoredClassCatalog bdbClassCatalog;
private final Class<T> dataClass;
public String getBdbStorePath() {
return bdbStorePath;
}
/**
* 设定BDB数据的存储目录。如果这个目录不存在，会被自动创建。
*
* @param storePath BDB数据的存储目录
*/
public void setBdbStorePath(final String storePath) {
this.bdbStorePath = storePath;
}
public long getBdbCheckpointBytes() {
return bdbCheckpointBytes;
}
/**
* 设置DBD的CheckpointBytes参数。默认值 10M。
*/
public void setBdbCheckpointBytes(final long dbdCheckpointBytes) {
this.bdbCheckpointBytes = dbdCheckpointBytes;
}
public long getBdbCacheSize() {
return bdbCacheSize;
}
/**
* 设置DBD的CacheSize参数。默认值 5M。
*/
public void setBdbCacheSize(final long dbdCacheSize) {
this.bdbCacheSize = dbdCacheSize;
}
public void init() throws DatabaseException {
if (null == bdbStorePath) {
throw new IllegalStateException("Member bdbStorePath is null!");
}
open();
}
private void open() throws DatabaseException {
final File bdbDir = new File(bdbStorePath);
if (!bdbDir.exists()) {
if (!bdbDir.mkdirs()) {
throw new RuntimeException("Fail to create the store directory(" + bdbStorePath
+ ") for bdb persistence store!");
}
}
final boolean readOnly = false;
final EnvironmentConfig envConfig = new EnvironmentConfig();
envConfig.setReadOnly(readOnly);
envConfig.setAllowCreate(true);
envConfig.setTransactional(true); // must setting
// checkpoint occupied after data file increase some bytes
envConfig.setConfigParam("je.checkpointer.bytesInterval", String
.valueOf(bdbCheckpointBytes));
final EnvironmentMutableConfig envMutableConfig = new EnvironmentMutableConfig();
envMutableConfig.setCacheSize(bdbCacheSize);
bdbEnvironment = new Environment(bdbDir, envConfig);
bdbEnvironment.setMutableConfig(envMutableConfig);
final DatabaseConfig dbConfig = new DatabaseConfig();
dbConfig.setReadOnly(readOnly);
dbConfig.setAllowCreate(!readOnly);
dbConfig.setSortedDuplicates(false);
dbConfig.setTransactional(true);
bdb = bdbEnvironment.openDatabase(null, MESSAGE_DBNAME, dbConfig);
// create class info db
final Database classDb = bdbEnvironment.openDatabase(null, MESSAGE_CLASS_DBNAME, dbConfig);
bdbClassCatalog = new StoredClassCatalog(classDb);
}
public void close() throws DatabaseException {
// close db first, then close enviroment
if (null != bdb) {
bdb.close();
bdb = null;
}
if (null != bdbClassCatalog) {
bdbClassCatalog.close();
bdbClassCatalog = null;
}
if (bdbEnvironment != null) {
bdbEnvironment.cleanLog();
bdbEnvironment.close();
bdbEnvironment = null;
}
}
/**
* 也可以使用 {@link #createBdbPersistenceStore(Class)} 来获得一个实例。
*
* @param clazz 存储数据的类型的class。
*/
public BdbPersistenceStore(final Class<T> clazz) {
dataClass = clazz;
}
/**
* 生成BdbPersistenceStore工厂方法。功能上和构造函数一样，形式上简单些。
*
* @param <DT> 存储数据的类型。
* @param dataType 存储数据的类型的class。
* @return 返回存储该数据类型的BdbPersistenceStore的泛型对象。
*/
public static <DT extends Serializable> BdbPersistenceStore<DT> createBdbPersistenceStore(
final Class<DT> dataType) {
return new BdbPersistenceStore<DT>(dataType);
}
/**
* 使用UUID字符串产生DatabaseEntry作为Key。
*/
private static DatabaseEntry generateKeyEntry() {
final String uuid = UUID.randomUUID().toString();
return generateKeyEntry(uuid);
}
/**
* 根据一个字符串产生DatabaseEntry作为Key。
*/
private static DatabaseEntry generateKeyEntry(final String key) {
final DatabaseEntry entry = new DatabaseEntry();
final EntryBinding keyBinding = TupleBinding.getPrimitiveBinding(String.class);
keyBinding.objectToEntry(key, entry);
return entry;
}
/**
* 从DatabaseEntry还原出Key
*/
private static String restoreKey(final DatabaseEntry entry) {
final EntryBinding keyBinding = TupleBinding.getPrimitiveBinding(String.class);
return (String) keyBinding.entryToObject(entry);
}
private DatabaseEntry generateDataEntry(final Object object) {
final DatabaseEntry entry = new DatabaseEntry();
final EntryBinding dataBinding = new SerialBinding(bdbClassCatalog, dataClass);
dataBinding.objectToEntry(object, entry);
return entry;
}
/**
* 从DatabaseEntry还原出数据
*/
private T restoreData(final DatabaseEntry entry) {
final EntryBinding dataBinding = new SerialBinding(bdbClassCatalog, dataClass);
@SuppressWarnings("unchecked")
final T data = (T) dataBinding.entryToObject(entry);
return data;
}
/**
* 写入一个对象。会自动生成一个与之对应的key。 <br>
* 如果出错，写入失败，忽略掉！
*/
// FIXME 忽略出错？ 是否有其它的解决办法？？
public void write(final T object) {
if (object != null) {
try {
bdb.put(null, generateKeyEntry(), generateDataEntry(object));
if (log.isTraceEnabled()) {
log.trace("write object to db: " + object);
}
} catch (final DatabaseException e) {
log.fatal("write message failed ", e);
}
}
}
/**
* 写入多个对象。 <br>
* 如果出错，写入失败，忽略掉！
*/
// FIXME 忽略出错？ 是否有其它的解决办法？？
public void batchWrite(final List<T> objectList) {
for (final T obj : objectList) {
write(obj);
}
}
/**
* 读数据。
*
* @return 返回读到的数据。 如果store中没有数据、或是读出错，则返回null。
*/
public Entry<String, T> read() {
SimpleEntry<String, T> entry = null;
Cursor cursor = null;
try {
cursor = bdb.openCursor(null, null);
final DatabaseEntry foundKey = new DatabaseEntry();
final DatabaseEntry foundData = new DatabaseEntry();
if (cursor.getNext(foundKey, foundData, LockMode.DEFAULT) == OperationStatus.SUCCESS) {
entry = new SimpleEntry<String, T>(restoreKey(foundKey), restoreData(foundData));
}
if (log.isTraceEnabled()) {
log.trace("read object from db");
}
} catch (final DatabaseException e) {
log.error("Don't warry, read message from db error, " + "late read again: "
+ e.getMessage());
} finally {
if (cursor != null) {
try {
cursor.close();
} catch (final DatabaseException e) {
// ignore
}
}
}
return entry;
}
/**
* 读数据。
*
* @return 返回读到的数据。 如果store中没有数据、或是读出错，则返回空的Map（即size为0的Map）。
*/
public Map<String, T> batchRead(final int count) {
final Map<String, T> map = new HashMap<String, T>(count);
Cursor cursor = null;
try {
cursor = bdb.openCursor(null, null);
final DatabaseEntry foundKey = new DatabaseEntry();
final DatabaseEntry foundData = new DatabaseEntry();
int readedNum = 0;
while (cursor.getNext(foundKey, foundData, LockMode.DEFAULT) == OperationStatus.SUCCESS
&& readedNum < count) {
map.put(restoreKey(foundKey), restoreData(foundData));
readedNum++;
}
if (log.isTraceEnabled()) {
log.trace("read object from db, count= " + readedNum);
}
} catch (final DatabaseException e) {
log.error("Don't warry, read message from db error, " + "late read again: "
+ e.getMessage());
} finally {
if (cursor != null) {
try {
cursor.close();
} catch (final DatabaseException e) {
// ignore
}
}
}
return map;
}
// FIXME 实现 忽略了 出错的情况。
public void delete(final String key) {
if (key == null) {
return;
}
Transaction transaction = null;
try {
final TransactionConfig txnConfig = new TransactionConfig();
txnConfig.setSync(true);
transaction = bdbEnvironment.beginTransaction(null, txnConfig);
if (log.isTraceEnabled()) {
log.trace("BDB: begin to transaction");
}
bdb.delete(transaction, generateKeyEntry(key));
if (log.isTraceEnabled()) {
log.trace("BDB: delete message key=" + key);
}
transaction.commit();
transaction = null;
if (log.isTraceEnabled()) {
log.trace("BDB: end of transaction");
}
} catch (final DatabaseException e) {
log.fatal("BDB: delete failed: " + e.getMessage());
} catch (final Throwable t) {
log.fatal("BDB: delete failed: " + t.getMessage());
} finally {
if (transaction != null) {
try {
transaction.abort();
} catch (final DatabaseException e1) {
}
}
}
}
public void delete(final List<String> keys) {
// TODO 优化这个方法，以避免多次开关事务！
for (final String key : keys) {
delete(key);
}
}
}