DACModule 核心是进行dac 一个帮助类，进行一些依赖的处理，方便在DACDaemon 中使用，同时官方为了支持自定义
基于动态类创建进行了扩展（DremioDaemon 处理的）
接口定义
参考类图
备注： 会发现包含两个SingletonRegistry （bootstrap的以及一个普通的，主要是不同优先级的服务处理），会将不同的服务模块注册到ioc 容器中，方便共享
使用
参考实现
包含了一个默认实现DACDaemonModule，以及几个方便测试的，如下
bootstrapRegistry 注册的服务
包含了bootstap context ，内存分配，集群协调器，master 选举服务，请求上下文等，会对于不同的节点角色提供不能的服务注册
参加如下
public void bootstrap(final Runnable shutdownHook, final SingletonRegistry bootstrapRegistry, ScanResult scanResult, DACConfig dacConfig, boolean isMaster) {
final DremioConfig config = dacConfig.getConfig();
final boolean embeddedZookeeper = config.getBoolean(DremioConfig.EMBEDDED_MASTER_ZK_ENABLED_BOOL);
final BootStrapContext bootStrapContext = new BootStrapContext(config, scanResult, bootstrapRegistry);
boolean isMasterless = config.isMasterlessEnabled();
bootstrapRegistry.bindSelf(bootStrapContext);
bootstrapRegistry.bind(BufferAllocator.class, bootStrapContext.getAllocator());
// Start cluster coordinator before all other services so that non master nodes can poll for master status
if (dacConfig.getClusterMode() == ClusterMode.LOCAL) {
bootstrapRegistry.bind(ClusterCoordinator.class, new LocalClusterCoordinator());
} else if (config.getBoolean(DremioConfig.NO_OP_CLUSTER_COORDINATOR_ENABLED)) {
isMasterless = true;
Preconditions.checkState(!isMaster);
bootstrapRegistry.bind(ClusterCoordinator.class, new NoOpClusterCoordinator());
} else {
// ClusterCoordinator has a runtime dependency on ZooKeeper. If no ZooKeeper server
// is present, ClusterCoordinator won't start, so this service should be initialized first.
final Provider<Integer> portProvider;
if (isMaster && embeddedZookeeper) {
ZkServer zkServer = new ZkServer(
config.getString(DremioConfig.EMBEDDED_MASTER_ZK_ENABLED_PATH_STRING),
config.getInt(DremioConfig.EMBEDDED_MASTER_ZK_ENABLED_PORT_INT),
dacConfig.autoPort);
bootstrapRegistry.bindSelf(zkServer);
portProvider = dacConfig.autoPort ? new Provider<Integer>(){
@Override
public Integer get() {
return bootstrapRegistry.lookup(ZkServer.class).getPort();
}} : null;
} else {
portProvider = null;
}
final ZKClusterCoordinator coord;
try {
coord = new ZKClusterCoordinator(config.getSabotConfig(), portProvider);
} catch (IOException e) {
throw new RuntimeException("Cannot instantiate the ZooKeeper cluster coordinator", e);
}
bootstrapRegistry.bind(ClusterCoordinator.class, coord);
}
// Start master election
if (isMaster && !config.getBoolean(DremioConfig.DEBUG_DISABLE_MASTER_ELECTION_SERVICE_BOOL)) {
bootstrapRegistry.bindSelf(new MasterElectionService(bootstrapRegistry.provider(ClusterCoordinator.class)));
}
final MasterStatusListener masterStatusListener;
final Provider<ClusterServiceSetManager> clusterServiceSetManagerProvider =
() -> bootstrapRegistry.provider(ClusterCoordinator.class).get();
if (!isMasterless) {
masterStatusListener = new MasterStatusListener(clusterServiceSetManagerProvider, config.getSabotConfig(), isMaster);
} else {
masterStatusListener =
new MasterlessStatusListener(clusterServiceSetManagerProvider, isMaster);
}
// start master status listener
bootstrapRegistry.bind(MasterStatusListener.class, masterStatusListener);
bootstrapRegistry.bindProvider(EngineId.class, Providers.of(null));
bootstrapRegistry.bindProvider(SubEngineId.class, Providers.of(null));
// Default request Context
bootstrapRegistry.bind(RequestContext.class,
RequestContext.empty()
.with(TenantContext.CTX_KEY, TenantContext.DEFAULT_SERVICE_CONTEXT)
.with(UserContext.CTX_KEY, UserContext.SYSTEM_USER_CONTEXT)
);
}普通registry注册的服务
普通registry注册的服务就比较多了，包含了不少能力，也是dremio 节点的一些核心能力模块
具体参考build 方法，注意此处也依赖了bootstrapRegistry，会将一些注册的binding 复制到普通registry 中
具体的代码比较多，核心是对于dremio的服务进行注册到ioc 容器中，包含了:执行服务（ExecutorService）
内存分配器工厂（集成了bootstrapRegistry的），ConnectionReader（数据连接读取的）rpc 处理，fabric 服务
身份服务，ConduitServiceRegistry，ConduitServer，ConduitInProcessChannelProvider，kv 存储,整理的一些参考注册服务（很多，将dremio
的核心服务都关联起来了，比如认证，反射加速，数据源数据，catalog服务，namespace 服务，taskpool 任务执行服务。。。。），参考如下
InformationSchemaServiceBlockingStub,DatasetCatalogServiceBlockingStub,ProjectRoleInitializer,ViewCreatorFactory,UserServer,ContextService,SabotContext, NodeEndpoint,NamespaceService,DatasetListingService,CoordExecService,HomeFileTool,SchedulerService,SystemOptionManager,OptionManager,SplitOrphansCleanerService,SpillService,CatalogService,CommandPool,LocalJobsService,SimpleJobRunner,ProvisioningService,ResourceAllocator,ExecutorSelectionService,MaestroForwarder,MaestroServicem,RuleBasedEngineSelector,foremenWorkManager,UserWorker,ContextInformationFactory,TaskPool,workloadTicketDepotService,JobResultsClientFactory,fragmentWorkManager,AccelerationManager,StatisticsService,JobsService,ReflectionService,ReflectionStatusService,ServerHealthMonitor,SupportService,NodeRegistration,SearchService,RestServerV2,APIServer,DremioServlet,SourceService,DremioFlightService,NessieService,UserPreferenceService,WebServer,TokenManager
说明
以上是一个简单的说明，如果希望完整的了解组件的关联关系，可以详细阅读的源码，部分组件我以前也简单的介绍过，可以参考，后边我也会详细介绍下
参考资料
dac/backend/src/main/java/com/dremio/dac/daemon/DACModule.java
dac/backend/src/main/java/com/dremio/dac/daemon/DACDaemonModule.java
dac/backend/src/test/java/com/dremio/dac/server/TestMultiMaster.java
dac/backend/src/test/java/com/dremio/dac/server/TestServerTracing.java
dac/backend/src/main/java/com/dremio/dac/daemon/DACDaemon.java
