hsqldb源码分析启动调试
hsqldb是java版的简化数据库,代码量比较少,对于学习数据库的设计是一个比较好的选择,
对于derby代码量比较大,mysql c++更复杂,所以就通过学习hsqldb来学习数据库的设计。
在这里可以下载到源码http://hsqldb.org/,源码包下org.hsqldb.test有很多的测试类,大家可以从这里开始调试学习hsqldb。
HyperSQL 数据库叫catalog,根据数据库存储方式不同分为几种:
• mem: stored entirely in RAM - without any persistence beyond the JVM process's life
• file: stored in filesystem files
客户端可以通过连接串不同指定不同的存储格式
Connection c = DriverManager.getConnection("jdbc:hsqldb:file:testdb", "SA", ""); Connection c = DriverManager.getConnection("jdbc:hsqldb:file:/opt/db/testdb", "SA", "");file:数据保存在文件 Connection c = DriverManager.getConnection("jdbc:hsqldb:mem:mymemdb", "SA", "");mem表示数据库只保存在内存 Connection c = DriverManager.getConnection("jdbc:hsqldb:res:org.my.path.resdb", "SA", ""); res表示压缩保存classpath java或者zip包中,内存解压使用
java -cp ../lib/hsqldb.jar org.hsqldb.server.Server --database.0 file:mydb --dbname.0 xdbHyperSQL HTTP Server http协议的服务器模式
java -cp ../lib/hsqldb.jar org.hsqldb.server.WebServer --database.0 file:mydb --dbname.0 xdbservlet容器启动服务器HyperSQL HTTP Servlet
try { Class.forName("org.hsqldb.jdbc.JDBCDriver" ); } catch (Exception e) { System.err.println("ERROR: failed to load HSQLDB JDBC driver."); e.printStackTrace(); return; }
Connection c = DriverManager.getConnection("jdbc:hsqldb:hsql://localhost/xdb", "SA", ""); 如果是hsql服务器模式则用:hsql:,http则用http:// Connection c = DriverManager.getConnection("jdbc:hsqldb:http://localhost/xdb", "SA", ""); 使用ssl连接到hsql和 http 服务器 Connection c = DriverManager.getConnection("jdbc:hsqldb:hsqls://localhost/xdb", "SA", ""); Connection c = DriverManager.getConnection("jdbc:hsqldb:https://localhost/xdb", "SA", "");
关闭服务器:使用参数shutdown=true,最后一个连接处理完了需要关闭服务器,会对内存数据进行处理(如果是文件的,则flush到文件),这个在测试场景下用得比较多。 Connection c = DriverManager.getConnection( "jdbc:hsqldb:file:/opt/db/testdb;shutdown=true", "SA", ""); 如果要重用已有的数据库,则用参数ifexists=true,如果数据库不存在,则抛异常。 Connection c = DriverManager.getConnection( "jdbc:hsqldb:file:/opt/db/testdb;ifexists=true", "SA", "");
public void handleConnection(Socket s) { Thread t; Runnable r; String ctn; printWithThread("handleConnection(" + s + ") entered"); if (!allowConnection(s)) { try { s.close(); } catch (Exception e) {} printWithThread("allowConnection(): connection refused"); printWithThread("handleConnection() exited"); return; } // Maybe set up socket options, SSL // Session tracing/callbacks, etc. if (socketFactory != null) { socketFactory.configureSocket(s); } if (serverProtocol == ServerConstants.SC_PROTOCOL_HSQL) { r = new ServerConnection(s, this); ctn = ((ServerConnection) r).getConnectionThreadName(); } else { r = new WebServerConnection(s, (WebServer) this); ctn = ((WebServerConnection) r).getConnectionThreadName(); } t = new Thread(serverConnectionThreadGroup, r, ctn); t.start(); printWithThread("handleConnection() exited"); }
从server的main函数输出参数中主要有几个:maxConnections 最大连接数限制, isSilent是否显示所有query,isRemoteOpen是否支持远程打开,不支持,isDaemon是否守护模式,acl指定访问控制权限文件路径,指定ip地址的黑白名单。acl文件格式参考http://hsqldb.org/doc/2.0/guide/listeners-chapt.html#N15C79
* +-----------------+-------------+----------+------------------------------+ * | OPTION | TYPE | DEFAULT | DESCRIPTION | * +-----------------+-------------+----------+------------------------------| * | --help | | | prints this message | * | --address | name|number | any | server inet address | * | --port | number | 9001/544 | port at which server listens | * | --database.i | [type]spec | 0=test | path of database i | * | --dbname.i | alias | | url alias for database i | * | --silent | true|false | true | false => display all queries | * | --trace | true|false | false | display JDBC trace messages | * | --tls | true|false | false | TLS/SSL (secure) sockets | * | --no_system_exit| true|false | false | do not issue System.exit() | * | --remote_open | true|false | false | can open databases remotely | * | --props | filepath | | file path of properties file | * +-----------------+-------------+----------+------------------------------+
maxConnections = serverProperties.getIntegerProperty( ServerProperties.sc_key_max_connections, 16); JavaSystem.setLogToSystem(isTrace()); isSilent = serverProperties.isPropertyTrue(ServerProperties.sc_key_silent); isRemoteOpen = serverProperties.isPropertyTrue( ServerProperties.sc_key_remote_open_db); isDaemon = serverProperties.isPropertyTrue(ServerProperties.sc_key_daemon);
当然openDatabase里面就是根据参数指定的database文件打开对应的数据库。
在database类的reopen方法中有几个对象,就是数据库操作相关的对象,无非就是数据库对象名称管理,权限管理,用户管理,shema管理,session管理,事务管理,日志管理,检查点管理,后续一个一个分析。
/** * Opens this database. The database should be opened after construction. * or reopened by the close(int closemode) method during a * "shutdown compact". Closes the log if there is an error. */ void reopen() { boolean isNew = false; setState(DATABASE_OPENING); try { nameManager = new HsqlNameManager(this); granteeManager = new GranteeManager(this); userManager = new UserManager(this); schemaManager = new SchemaManager(this); persistentStoreCollection = new PersistentStoreCollectionDatabase(); isReferentialIntegrity = true; sessionManager = new SessionManager(this); collation = collation.newDatabaseInstance(); dbInfo = DatabaseInformation.newDatabaseInformation(this); txManager = new TransactionManager2PL(this); lobManager.createSchema(); sessionManager.getSysLobSession().setSchema( SqlInvariants.LOBS_SCHEMA); schemaManager.setSchemaChangeTimestamp(); schemaManager.createSystemTables(); // completed metadata logger.openPersistence(); isNew = logger.isNewDatabase; if (isNew) { String username = urlProperties.getProperty("user", "SA"); String password = urlProperties.getProperty("password", ""); userManager.createFirstUser(username, password); schemaManager.createPublicSchema(); lobManager.initialiseLobSpace(); logger.checkpoint(false); } lobManager.open(); dbInfo.setWithContent(true); checkpointRunner = new CheckpointRunner(); } catch (Throwable e) { logger.closePersistence(Database.CLOSEMODE_IMMEDIATELY); logger.releaseLock(); setState(DATABASE_SHUTDOWN); clearStructures(); DatabaseManager.removeDatabase(this); if (!(e instanceof HsqlException)) { e = Error.error(ErrorCode.GENERAL_ERROR, e); } logger.logSevereEvent("could not reopen database", e); throw (HsqlException) e; } setState(DATABASE_ONLINE); }
下一节分析handleConnection的处理