ShardingSphere~7

ShardingProxy服务器处理框架

启动：shardingsphere-proxy-bootstrap

@NoArgsConstructor(access = AccessLevel.PRIVATE)
public final class Bootstrap {
    public static void main(final String[] args) throws IOException, SQLException {
        BootstrapArguments bootstrapArgs = new BootstrapArguments(args);
        YamlProxyConfiguration yamlConfig = ProxyConfigurationLoader.load(bootstrapArgs.getConfigurationPath());
        createBootstrapInitializer(yamlConfig).init(yamlConfig, bootstrapArgs.getPort());
    }
    private static BootstrapInitializer createBootstrapInitializer(final YamlProxyConfiguration yamlConfig) {
        return null == yamlConfig.getServerConfiguration().getGovernance() ? new StandardBootstrapInitializer() : new GovernanceBootstrapInitializer();
    }
}

AbstractBootstrapInitializer 初始化，看到根据配置初始化各种组件，事件监听，扩展任务执行器等，最终启动proxy

    @Override
    public final void init(final YamlProxyConfiguration yamlConfig, final int port) throws SQLException {
        ProxyConfiguration proxyConfig = getProxyConfiguration(yamlConfig);
        MetaDataContexts metaDataContexts = decorateMetaDataContexts(createMetaDataContexts(proxyConfig));
        for (MetaDataAwareEventSubscriber each : ShardingSphereServiceLoader.getSingletonServiceInstances(MetaDataAwareEventSubscriber.class)) {
            each.setMetaDataContexts(metaDataContexts);
            ShardingSphereEventBus.getInstance().register(each);
        }
        String xaTransactionMangerType = metaDataContexts.getProps().getValue(ConfigurationPropertyKey.XA_TRANSACTION_MANAGER_TYPE);
        TransactionContexts transactionContexts = decorateTransactionContexts(createTransactionContexts(metaDataContexts), xaTransactionMangerType);
        ProxyContext.getInstance().init(metaDataContexts, transactionContexts);
        setDatabaseServerInfo();
        initScalingWorker(yamlConfig);
        shardingSphereProxy.start(port);
    }

proxy服务器启动

public final class ShardingSphereProxy {
    private EventLoopGroup bossGroup;
    private EventLoopGroup workerGroup;
    @SneakyThrows(InterruptedException.class)
    public void start(final int port) {
        try {
            createEventLoopGroup();
            ServerBootstrap bootstrap = new ServerBootstrap();
            initServerBootstrap(bootstrap);
            ChannelFuture future = bootstrap.bind(port).sync();
            log.info("ShardingSphere-Proxy start success.");
            future.channel().closeFuture().sync();
        } finally {
            workerGroup.shutdownGracefully();
            bossGroup.shutdownGracefully();
            BackendExecutorContext.getInstance().getExecutorEngine().close();
        }
    }
    
    private void createEventLoopGroup() {
        bossGroup = Epoll.isAvailable() ? new EpollEventLoopGroup(1) : new NioEventLoopGroup(1);
        workerGroup = Epoll.isAvailable() ? new EpollEventLoopGroup() : new NioEventLoopGroup();
    }
    
    private void initServerBootstrap(final ServerBootstrap bootstrap) {
        bootstrap.group(bossGroup, workerGroup)
                .channel(Epoll.isAvailable() ? EpollServerSocketChannel.class : NioServerSocketChannel.class)
                .option(ChannelOption.SO_BACKLOG, 128)
                .option(ChannelOption.WRITE_BUFFER_WATER_MARK, new WriteBufferWaterMark(8 * 1024 * 1024, 16 * 1024 * 1024))
                .option(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT)
                .childOption(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT)
                .childOption(ChannelOption.TCP_NODELAY, true)
                .handler(new LoggingHandler(LogLevel.INFO))
                .childHandler(new ServerHandlerInitializer(FrontDatabaseProtocolTypeFactory.getDatabaseType()));
    }
}

在handler中解码请求并处理相关请求

public final class ServerHandlerInitializer extends ChannelInitializer<SocketChannel> {
    
    private final DatabaseType databaseType;
    
    @Override
    protected void initChannel(final SocketChannel socketChannel) {
        DatabaseProtocolFrontendEngine databaseProtocolFrontendEngine = DatabaseProtocolFrontendEngineFactory.newInstance(databaseType);
        ChannelPipeline pipeline = socketChannel.pipeline();
        pipeline.addLast(new PacketCodec(databaseProtocolFrontendEngine.getCodecEngine()));
        pipeline.addLast(new FrontendChannelInboundHandler(databaseProtocolFrontendEngine));
    }
}

处理各种读写事件

public final class FrontendChannelInboundHandler extends ChannelInboundHandlerAdapter {
    
    private final DatabaseProtocolFrontendEngine databaseProtocolFrontendEngine;
    
    private final BackendConnection backendConnection;
    
    private volatile boolean authenticated;
    
    public FrontendChannelInboundHandler(final DatabaseProtocolFrontendEngine databaseProtocolFrontendEngine) {
        this.databaseProtocolFrontendEngine = databaseProtocolFrontendEngine;
        TransactionType transactionType = TransactionType.valueOf(ProxyContext.getInstance().getMetaDataContexts().getProps().getValue(ConfigurationPropertyKey.PROXY_TRANSACTION_TYPE));
        backendConnection = new BackendConnection(transactionType);
    }
    
    @Override
    public void channelActive(final ChannelHandlerContext context) {
        int connectionId = databaseProtocolFrontendEngine.getAuthenticationEngine().handshake(context);
        ConnectionThreadExecutorGroup.getInstance().register(connectionId);
        backendConnection.setConnectionId(connectionId);
    }
    
    @Override
    public void channelRead(final ChannelHandlerContext context, final Object message) {
        if (!authenticated) {
            authenticated = authenticate(context, (ByteBuf) message);
            return;
        }
        ProxyStateContext.execute(context, message, databaseProtocolFrontendEngine, backendConnection);
    }
    
    private boolean authenticate(final ChannelHandlerContext context, final ByteBuf message) {
        try (PacketPayload payload = databaseProtocolFrontendEngine.getCodecEngine().createPacketPayload(message)) {
            AuthenticationResult authResult = databaseProtocolFrontendEngine.getAuthenticationEngine().authenticate(context, payload);
            if (authResult.isFinished()) {
                backendConnection.setGrantee(new Grantee(authResult.getUsername(), authResult.getHostname()));
                backendConnection.setCurrentSchema(authResult.getDatabase());
            }
            return authResult.isFinished();
            // CHECKSTYLE:OFF
        } catch (final Exception ex) {
            // CHECKSTYLE:ON
            log.error("Exception occur: ", ex);
            context.writeAndFlush(databaseProtocolFrontendEngine.getCommandExecuteEngine().getErrorPacket(ex, backendConnection));
            context.close();
        }
        return false;
    }
    
    @Override
    public void channelInactive(final ChannelHandlerContext context) {
        context.fireChannelInactive();
        closeAllResources();
    }
    
    private void closeAllResources() {
        ConnectionThreadExecutorGroup.getInstance().unregisterAndAwaitTermination(backendConnection.getConnectionId());
        PrimaryVisitedManager.clear();
        backendConnection.closeResultSets();
        backendConnection.closeStatements();
        backendConnection.closeConnections(true);
        backendConnection.closeFederateExecutor();
        databaseProtocolFrontendEngine.release(backendConnection);
    }
    
    @Override
    public void channelWritabilityChanged(final ChannelHandlerContext context) {
        if (context.channel().isWritable()) {
            backendConnection.getResourceLock().doNotify();
        }
    }
}

ProxyStateContext类中对应各种状态执行对应的动作

    static {
        STATES.put(StateType.OK, new OKProxyState());
        STATES.put(StateType.LOCK, new LockProxyState());
        STATES.put(StateType.CIRCUIT_BREAK, new CircuitBreakProxyState());
    }

进入执行

public final class OKProxyState implements ProxyState {
    
    @Override
    public void execute(final ChannelHandlerContext context, final Object message, final DatabaseProtocolFrontendEngine databaseProtocolFrontendEngine, final BackendConnection backendConnection) {
        boolean supportHint = ProxyContext.getInstance().getMetaDataContexts().getProps().<Boolean>getValue(ConfigurationPropertyKey.PROXY_HINT_ENABLED);
        boolean isOccupyThreadForPerConnection = databaseProtocolFrontendEngine.getFrontendContext().isOccupyThreadForPerConnection();
        ExecutorService executorService = CommandExecutorSelector.getExecutorService(
                isOccupyThreadForPerConnection, supportHint, backendConnection.getTransactionStatus().getTransactionType(), backendConnection.getConnectionId());
        executorService.execute(new CommandExecutorTask(databaseProtocolFrontendEngine, backendConnection, context, message));
    }
}