增加Router详解

hdfs/router启动详解.md

@@ -63,33 +63,107 @@ addService(this.cacheUpdater);
 
 启动主要是Router的serviceStart函数触发，最终调用StateStoreDriver的init函数，用于初始化driver。核心函数为initDriver和initRecordStorage。
 
-#### StateStoreFileImpl 
+其中initRecordStorage针对每个record stores都需要调用，如下：
+```java
+for (Class<? extends BaseRecord> cls : records) {
+  String recordString = StateStoreUtils.getRecordName(cls);
+  if (!initRecordStorage(recordString, cls)) {
+    LOG.error("Cannot initialize record store for {}", cls.getSimpleName());
+    return false;
+  }
+}
+```
+
+#### StateStoreFileImpl or StateStoreFileSystemImpl
 
 ##### initDriver
 
+对于当前的StateStore初始化比较简单，主要是检查本地文件夹是否存在，不存在就创建。大致代码如下：
+
+```java
+public boolean initDriver() {
+    String rootDir = getRootDir();
+      if (rootDir == null) {
+        LOG.error("Invalid root directory, unable to initialize driver.");
+        return false;
+      }
+
+      // Check root path
+      if (!exists(rootDir)) {
+        if (!mkdir(rootDir)) {
+          LOG.error("Cannot create State Store root directory {}", rootDir);
+          return false;
+        }
+      }
+    // ... 省略 ...
+    int threads = getConcurrentFilesAccessNumThreads();
+      this.concurrentStoreAccessPool =
+          new ThreadPoolExecutor(threads, threads, 0L, TimeUnit.MILLISECONDS,
+              new LinkedBlockingQueue<>(),
+              new ThreadFactoryBuilder()
+                  .setNameFormat("state-store-file-based-concurrent-%d")
+                  .setDaemon(true).build());
+    return true;
+  }
+```
 
 ##### initRecordStorage
+和initDriver类似，支持针对每个State Store创建对应的目录，目录名称使用state store的className。
 
-
-#### StateStoreFileSystemImpl
-
-initDriver
-
-initRecordStorage
+```java
+public <T extends BaseRecord> boolean initRecordStorage(
+      String className, Class<T> recordClass) {
+    String dataDirPath = getRootDir() + "/" + className;
+    // Create data directories for files
+    if (!exists(dataDirPath)) {
+      LOG.info("{} data directory doesn't exist, creating it", dataDirPath);
+      if (!mkdir(dataDirPath)) {
+        LOG.error("Cannot create data directory {}", dataDirPath);
+        return false;
+      }
+    }
+    return true;
+  }
+```
 
 
 #### StateStoreMySQLImpl
 
-initDriver
+##### initDriver
+核心逻辑就是创建Mysql连接。Mysql连接封装为类MySQLStateStoreHikariDataSourceConnectionFactory。
+```java
+MySQLStateStoreHikariDataSourceConnectionFactory(Configuration conf) {
+    Properties properties = new Properties();
+    properties.setProperty("jdbcUrl", conf.get(StateStoreMySQLImpl.CONNECTION_URL));
+    properties.setProperty("username", conf.get(StateStoreMySQLImpl.CONNECTION_USERNAME));
+    properties.setProperty("password", conf.get(StateStoreMySQLImpl.CONNECTION_PASSWORD));
+    properties.setProperty("driverClassName", conf.get(StateStoreMySQLImpl.CONNECTION_DRIVER));
 
-initRecordStorage
+    // Include hikari connection properties
+    properties.putAll(conf.getPropsWithPrefix(HIKARI_PROPS));
+
+    HikariConfig hikariConfig = new HikariConfig(properties);
+    this.dataSource = new HikariDataSource(hikariConfig);
+}
+```
+
+##### initRecordStorage
+
+zai StateStoreMySQLImpl当中，每个state store 对应一张表。建表语句如下：
+```sql
+CREATE TABLE <className> (
+   recordKey VARCHAR (255) NOT NULL,
+   recordValue VARCHAR (2047) NOT NULL,
+   PRIMARY KEY(recordKey))
+)
+```
 
 
 #### StateStoreZooKeeperImpl
 
-initDriver
+##### initDriver
 
-initRecordStorage
+##### initRecordStorage
 
 
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