目錄結構
在官網中也有更詳細的介紹，下面我只對目錄結構做一個簡單介紹即可，感興趣的朋友可以參考官網文檔.http://www.hivemq.com/docs/hivemq/latest/#installation
目錄結構
bin
包含hivemq.jar以及一些啟動腳本
conf
包含config.xml、logback.xml以及plugin的配置文件
examples是一些示例組網場景的示例配置
data
metadata存放版本信息(加密過)
persistence存放著所有持久化信息的文件、以及備份文件。包含client_session_subscriptions、client_sessions、outgoing_message_flow、incomming_message_flow、publish_payloads、queued_messages、retained_messages等。
diagnostics
存放著診斷模式下診斷信息，包括系統信息、網絡接口信息、jvm信息、插件信息等等。方便開發者排查問題。
license
存放hivemq授權license文件。
log
存放日志
plugins
第三方插件目錄
啟動
既然它是一個java程序,那么我們就從它的main方法開始我們的hivemq源碼之路。
main
public class HiveMQServer {
private static final Logger LOGGER = LoggerFactory.getLogger(HiveMQServer.class);
private final NettyServer nettyServer;
private final ClusterConfigurationService clusterConfigurationService;
private final PluginBrokerCallbackHandler pluginBrokerCallbackHandler;
private final PluginInformationStore pluginInformationStore;
private final Provider<ClusterJoiner> clusterJoinerProvider;
@Inject
HiveMQServer(NettyServer nettyServer,
ClusterConfigurationService clusterConfigurationService,
PluginBrokerCallbackHandler pluginBrokerCallbackHandler,
PluginInformationStore pluginInformationStore,
Provider<ClusterJoiner> clusterJoinerProvider) {
this.nettyServer = nettyServer;
this.clusterConfigurationService = clusterConfigurationService;
this.pluginBrokerCallbackHandler = pluginBrokerCallbackHandler;
this.pluginInformationStore = pluginInformationStore;
this.clusterJoinerProvider = clusterJoinerProvider;
}
public void start() throws InterruptedException, ExecutionException {
//啟動netty server
this.nettyServer.start().sync();
//通知OnBrokerStart事件
fireOnBrokerStart();
//加入cluster
joinCluster();
//啟動對應承載在netty上的Listener，并打印出這些Listener啟動結果信息。請參考Linstener配置請參考http://www.hivemq.com/docs/hivemq/latest/#configuration-chapter
ListenableFuture<List<ListenerStartResult>> startFuture = this.nettyServer.startListeners();
List<ListenerStartResult> startResults = startFuture.get();
new ListenerStartResultLogger(startResults).log();
}
private void joinCluster() {
//根據配置確定是否加入cluster
if (!this.clusterConfigurationService.isEnabled()) {
return;
}
try {
//使用ClusterJoiner類進行連接jgroup，組成cluster。
ClusterJoiner clusterJoiner = this.clusterJoinerProvider.get();
ListenableFuture<Void> future = clusterJoiner.join();
future.get();
} catch (Exception e) {
if (e.getCause() instanceof DuplicateOrInvalidLicenseException) {
LOGGER.error("Found duplicate or invalid license file in the cluster. Shutting down HiveMQ");
} else if (e.getCause() instanceof DifferentConfigurationException) {
LOGGER.error("The configuration of this HiveMQ instance is different form the other instances in the cluster. Shutting down HiveMQ");
} else {
LOGGER.error("Could not join cluster. Shutting down HiveMQ.", e);
}
if (e.getCause() instanceof UnrecoverableException) {
throw ((UnrecoverableException) e.getCause());
}
throw new UnrecoverableException(false);
}
}
//通知對應plugin broker已經啟動
private void fireOnBrokerStart() {
LOGGER.trace("Calling all OnBrokerStart Callbacks");
printPluginInformations();
this.pluginBrokerCallbackHandler.onStart();
}
public static void main(String[] args) throws InterruptedException, ExecutionException {
LOGGER.info("Starting HiveMQ Server");
long startTime = System.nanoTime();
//初始化SystemInformation，可以通過環境變量來分別設置conf、plugins、log、license等目錄。
//請參考hivemq spi SystemInformation
LOGGER.trace("Initializing HiveMQ home directory");
HiveMQSystemInformation systemInformation = new HiveMQSystemInformation(true);
//創建MetricRegistry
//請參考開源框架Metrics
LOGGER.trace("Creating MetricRegistry");
MetricRegistry metricRegistry = new MetricRegistry();
//增加統計Listener
metricRegistry.addListener(new StatisticsListener());
//初始化日志
LOGGER.trace("Initializing Logging");
LogConfigurator.init(systemInformation.getConfigFolder(), metricRegistry);
//增加未處理異常攔截,并對其進行優雅處理
LOGGER.trace("Initializing Exception handlers");
RecoverableExceptionHandler.init();
//初始化ConfigurationService,并讀取conf/config.xml文件，加載用戶配置
//請參考hivemq spi ConfigurationService,
LOGGER.trace("Initializing configuration");
HiveMQConfigurationService hiveMQConfigurationService = HiveMQConfigurationServiceFactory.create(systemInformation);
//創建Clusterid提供者。
ClusterIdProducer clusterIdProducer = new ClusterIdProducer();
if (hiveMQConfigurationService.clusterConfiguration().isEnabled()) {
LOGGER.info("This node's cluster-ID is {}", clusterIdProducer.get());
}
//根據原有版本，判斷是否需要做持久化數據的migration，如需要進行migration，因為可以配置每個數據的使用策略(file/memory)，所以每個數據分別進行migration
LOGGER.trace("Checking for migrations");
Map<MigrationType, Set<String>> neededMigrations = Migrations.getNeededMigrations(systemInformation);
Injector injector = null;
if (neededMigrations.size() > 0) {
LOGGER.warn("HiveMQ has been updated, migrating persistent data to new version !");
neededMigrations.keySet().forEach(type -> LOGGER.debug("{} needs to be migrated", type));
//因為migration也是依賴guice來做容器，所以migration也會創建一個injector
injector = Bootstrap.createInjector(systemInformation, hiveMQConfigurationService, clusterIdProducer);
Migrations.start(injector, neededMigrations);
}
//升級完成,將升級的最新版本信息，持久化到文件中，以便下次啟動進行判斷
Migrations.finish(systemInformation, hiveMQConfigurationService);
//初始化guice
LOGGER.trace("Initializing Guice");
injector = Bootstrap.createInjector(systemInformation, metricRegistry, hiveMQConfigurationService, clusterIdProducer, injector);
//從guice中獲得HiveMQServer實例，并啟動它
HiveMQServer server = injector.getInstance(HiveMQServer.class);
server.start();
//對EXodus日志級別做修改
LogConfigurator.addXodusLogModificator();
LOGGER.info("Started HiveMQ in {}ms", TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startTime));
//hivemq版本升級檢查器，會連接hivemq官網判斷是否有新版本升級。可以在配置文件中設置不檢查
UpdateChecker updateChecker = injector.getInstance(UpdateChecker.class);
updateChecker.start();
}
//根據加載出來的所有plugin打印plugin信息
//請參考hivemq spi @Information
private void printPluginInformations() {
Set<PluginInformation> pluginInformations = this.pluginInformationStore.getPluginInformations();
pluginInformations.forEach(pluginInformation ->
LOGGER.info("Loaded Plugin {} - v{}", pluginInformation.getName(), pluginInformation.getVersion())
);
}
}
Bootstrap & Guice Modules
它是采用Guice作為di框架，那么我們就從Bootstrap開始看它包含了哪些Module以及簡單介紹下這些Module主要是注入哪些對應處理代碼。
public class Bootstrap {
private static final Logger LOGGER = LoggerFactory.getLogger(Bootstrap.class);
public static Injector createInjector(SystemInformation systemInformation, MetricRegistry metricRegistry, HiveMQConfigurationService hiveMQConfigurationService, ClusterIdProducer clusterIdProducer, Injector injector) {
//根據系統變量判斷是否開啟診斷模式
if (!Boolean.parseBoolean(System.getProperty("diagnosticMode"))) {
LOGGER.trace("Turning Guice stack traces off");
System.setProperty("guice_include_stack_traces", "OFF");
}
//加載所有PluginModule
//請參考hivemq spi PluginModule
//后續會專門講解plugin是如何加載的
List<PluginModule> pluginModules = new PluginBootstrap().create(systemInformation.getPluginFolder());
ImmutableList.Builder<AbstractModule> builder = ImmutableList.builder();
builder.add(
//系統信息
new SystemInformationModule(systemInformation),
//注冊cache的生命周期范圍
new ScopeModule(),
//增加@PostConstruct、@PreDestroy注解處理
new LifecycleModule(),
//配置的Module
new ConfigurationModule(hiveMQConfigurationService, clusterIdProducer),
//netty所有handler、以及listenser等module
new NettyModule(),
//內部module
new InternalModule(),
//plugin callback module，主要處理plugin注冊cabllback后回調
new PluginCallbackModule(),
//為方法增加cache的module
new MethodCacheModule(),
//持久化module
new PersistenceModule(injector),
//統計的module
new MetricModule(metricRegistry),
//流量監控module
new TrafficShapingModule(),
//cluster module
new ClusterModule(),
//plugin提供service的module
new ServiceModule(pluginModules),
//license的解析、驗證、限制module
new LicensingModule(),
//更新hivemq程序的module
new UpdateModule(),
//診斷模式module
new DiagnosticModule());
builder.addAll(pluginModules);
return Guice.createInjector(Stage.PRODUCTION, builder.build());
}
//創建數據升級的Injector，這個較上面的module加載的少點而已。
public static Injector createInjector(SystemInformation systemInformation,
HiveMQConfigurationService hiveMQConfigurationService,
ClusterIdProducer clusterIdProducer) {
ImmutableList.Builder<AbstractModule> builder = ImmutableList.builder();
builder.add(
new SystemInformationModule(systemInformation),
new ConfigurationModule(hiveMQConfigurationService, clusterIdProducer),
new BridgeModule(),
new ScopeModule(),
new LifecycleModule());
return Guice.createInjector(Stage.PRODUCTION, builder.build());
}
}
