数据库路由中间件MyCat - 源代码篇（11）
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4.配置模块
每个MyCatServer初始化时，会初始化： MyCatServer.java:
public static final String NAME = "MyCat";private static final long LOG_WATCH_DELAY = 60000L;private static final long TIME_UPDATE_PERIOD = 20L;private static final MycatServer INSTANCE = new MycatServer();private static final Logger LOGGER = LoggerFactory.getLogger("MycatServer");private final RouteService routerService;private final CacheService cacheService;private Properties dnIndexProperties;//AIO连接群组private AsynchronousChannelGroup[] asyncChannelGroups;private volatile int channelIndex = 0;//全局序列号private final MyCATSequnceProcessor sequnceProcessor = new MyCATSequnceProcessor();private final DynaClassLoader catletClassLoader;private final SQLInterceptor sqlInterceptor;private volatile int nextProcessor;private BufferPool bufferPool;private boolean aio = false;//XA事务全局ID生成private final AtomicLong xaIDInc = new AtomicLong();private MycatServer() { //读取文件配置
this.config = new MycatConfig(); //定时线程池，单线程线程池
scheduler = Executors.newSingleThreadScheduledExecutor(); //SQL记录器
this.sqlRecorder = new SQLRecorder(config.getSystem()
.getSqlRecordCount()); /**
* 是否在线，MyCat manager中有命令控制
* | offline | Change MyCat status to OFF |
* | online | Change MyCat status to ON |
*/
this.isOnline = new AtomicBoolean(true); //缓存服务初始化
cacheService = new CacheService(); //路由计算初始化
routerService = new RouteService(cacheService); // load datanode active index from properties
dnIndexProperties = loadDnIndexProps(); try { //SQL解析器
sqlInterceptor = (SQLInterceptor) Class.forName(
config.getSystem().getSqlInterceptor()).newInstance();
} catch (Exception e) { throw new RuntimeException(e);
} //catlet加载器
catletClassLoader = new DynaClassLoader(SystemConfig.getHomePath()
+ File.separator + "catlet", config.getSystem()
.getCatletClassCheckSeconds()); //记录启动时间
this.startupTime = TimeUtil.currentTimeMillis();
}第一步是读取文件配置，主要是三个文件：schema.xml，rule.xml和server.xml. 读取后的配置会加载到MyCatConfig中。 MyCatConfig.java:
public MycatConfig() {//读取schema.xml，rule.xml和server.xmlConfigInitializer confInit = new ConfigInitializer(true);this.system = confInit.getSystem();this.users = confInit.getUsers();this.schemas = confInit.getSchemas();this.dataHosts = confInit.getDataHosts();this.dataNodes = confInit.getDataNodes();for (PhysicalDBPool dbPool : dataHosts.values()) {
dbPool.setSchemas(getDataNodeSchemasOfDataHost(dbPool.getHostName()));
}this.quarantine = confInit.getQuarantine();this.cluster = confInit.getCluster();//初始化重加载配置时间this.reloadTime = TimeUtil.currentTimeMillis();this.rollbackTime = -1L;this.status = RELOAD;//配置加载锁this.lock = new ReentrantLock();
}它们都通过ConfigInitializer读取：
public ConfigInitializer(boolean loadDataHost) { //读取schema.xml
SchemaLoader schemaLoader = new XMLSchemaLoader(); //读取server.xml
XMLConfigLoader configLoader = new XMLConfigLoader(schemaLoader);
schemaLoader = null; //加载配置
this.system = configLoader.getSystemConfig(); this.users = configLoader.getUserConfigs(); this.schemas = configLoader.getSchemaConfigs(); //是否重新加载DataHost和对应的DataNode
if (loadDataHost) { this.dataHosts = initDataHosts(configLoader); this.dataNodes = initDataNodes(configLoader);
} //权限管理
this.quarantine = configLoader.getQuarantineConfig(); this.cluster = initCobarCluster(configLoader); //不同类型的全局序列处理器的配置加载
if (system.getSequnceHandlerType() == SystemConfig.SEQUENCEHANDLER_MYSQLDB) {
IncrSequenceMySQLHandler.getInstance().load();
} if (system.getSequnceHandlerType() == SystemConfig.SEQUENCEHANDLER_LOCAL_TIME) {
IncrSequenceTimeHandler.getInstance().load();
} //检查user与schema配置对应以及schema配置不为空
this.checkConfig();
}4.1 rule.xml
读取schema之前会先读取rule.xml。 XmlSchemaLoader.java:
public XMLSchemaLoader(String schemaFile, String ruleFile) { //先读取rule.xml
XMLRuleLoader ruleLoader = new XMLRuleLoader(ruleFile); this.tableRules = ruleLoader.getTableRules();
ruleLoader = null; this.dataHosts = new HashMap<String, DataHostConfig>(); this.dataNodes = new HashMap<String, DataNodeConfig>(); this.schemas = new HashMap<String, SchemaConfig>(); //读取加载schema配置
this.load(DEFAULT_DTD, schemaFile == null ? DEFAULT_XML : schemaFile);
}public XMLSchemaLoader() { this(null, null);
}XMLRuleLoader.java:
public XMLRuleLoader(String ruleFile) { // this.rules = new HashSet<RuleConfig>();
//rule名 -> rule
this.tableRules = new HashMap<String, TableRuleConfig>(); //function名 -> 具体分片算法
this.functions = new HashMap<String, AbstractPartitionAlgorithm>(); //默认为：/rule.dtd和/rule.xml
load(DEFAULT_DTD, ruleFile == null ? DEFAULT_XML : ruleFile);
}public XMLRuleLoader() { this(null);
}private void load(String dtdFile, String xmlFile) {
InputStream dtd = null;
InputStream xml = null; try {
dtd = XMLRuleLoader.class.getResourceAsStream(dtdFile);
xml = XMLRuleLoader.class.getResourceAsStream(xmlFile); //读取出语意树
Element root = ConfigUtil.getDocument(dtd, xml)
.getDocumentElement(); //加载Function
loadFunctions(root); //加载TableRule
loadTableRules(root);
} catch (ConfigException e) { throw e;
} catch (Exception e) { throw new ConfigException(e);
} finally { if (dtd != null) { try {
dtd.close();
} catch (IOException e) {
}
} if (xml != null) { try {
xml.close();
} catch (IOException e) {
}
}
}
}ConfigUtil.java解析语意树:
public static Document getDocument(final InputStream dtd, InputStream xml) throws ParserConfigurationException,
SAXException, IOException {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setValidating(true);
factory.setNamespaceAware(false);
DocumentBuilder builder = factory.newDocumentBuilder();
builder.setEntityResolver(new EntityResolver() { @Override
public InputSource resolveEntity(String publicId, String systemId) { return new InputSource(dtd);
}
});
builder.setErrorHandler(new ErrorHandler() { @Override
public void warning(SAXParseException e) {
} @Override
public void error(SAXParseException e) throws SAXException { throw e;
} @Override
public void fatalError(SAXParseException e) throws SAXException { throw e;
}
}); return builder.parse(xml);
}加载functions，XmlRuleLoader.java
private void loadFunctions(Element root) throws ClassNotFoundException,
InstantiationException, IllegalAccessException,
InvocationTargetException {
NodeList list = root.getElementsByTagName("function"); for (int i = 0, n = list.getLength(); i < n; ++i) {
Node node = list.item(i); if (node instanceof Element) {
Element e = (Element) node; //获取name标签
String name = e.getAttribute("name"); //如果Map已有，则function重复
if (functions.containsKey(name)) { throw new ConfigException("rule function " + name
+ " duplicated!");
} //获取class标签
String clazz = e.getAttribute("class"); //根据class利用反射新建分片算法
AbstractPartitionAlgorithm function = createFunction(name, clazz);
ParameterMapping.mapping(function, ConfigUtil.loadElements(e)); //每个AbstractPartitionAlgorithm可能会实现init来初始化
function.init(); //放入functions map
functions.put(name, function);
}
}
}private AbstractPartitionAlgorithm createFunction(String name, String clazz)
throws ClassNotFoundException, InstantiationException,
IllegalAccessException, InvocationTargetException {
Class<?> clz = Class.forName(clazz); //判断是否继承AbstractPartitionAlgorithm
if (!AbstractPartitionAlgorithm.class.isAssignableFrom(clz)) { throw new IllegalArgumentException("rule function must implements "
+ AbstractPartitionAlgorithm.class.getName() + ", name=" + name);
}
return (AbstractPartitionAlgorithm) clz.newInstance();
}加载所有的function的node，每一个node就是一个AbstractPartitionAlgorithm，并放入functions这个map中；
private final Map<String, TableRuleConfig> tableRules;
对于每一个node，通过反射新建对应参数的AbstractPartitionAlgorithm。这样，所有的function就加载到了functions这个map中。 同理，加载TableRule，就加上了function是否存在的判断：
/**
* tableRule标签结构：
* <tableRule name="sharding-by-month">
* <rule>
* <columns>create_date</columns>
* <algorithm>partbymonth</algorithm>
* </rule>
* </tableRule>
* @param root
* @throws SQLSyntaxErrorException
*/private void loadTableRules(Element root) throws SQLSyntaxErrorException { //获取每个tableRule标签
NodeList list = root.getElementsByTagName("tableRule"); for (int i = 0, n = list.getLength(); i < n; ++i) {
Node node = list.item(i); if (node instanceof Element) {
Element e = (Element) node; //先判断是否重复
String name = e.getAttribute("name"); if (tableRules.containsKey(name)) { throw new ConfigException("table rule " + name
+ " duplicated!");
} //获取rule标签更多网易技术、产品、运营经验分享请点击。
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