Gradle中ListenerManager的初始化流程

接口实现    public void addListener(Object listener) {               //interface 1        synchronized (lock) {            if (allListeners.add(listener)) {                for (BroadcastDispatch<?> broadcaster : dispatchers.values()) {                    maybeAddToDispatcher(broadcaster, listener);                }            }        }    }------------------------------------------------------------------------------public void useLogger(Object logger) {//interface 2        synchronized (lock) {            if (allLoggers.add(logger)) {                for (LoggerDispatch dispatch : loggers.values()) {                    dispatch.maybeSetLogger(logger);                }            }        }    }--------------------------------------------------------------------------------public <T> T getBroadcaster(Class<T> listenerClass) {//interface 3        return getBroadcasterInternal(listenerClass).getSource();    }private <T> ListenerBroadcast<T> getBroadcasterInternal(Class<T> listenerClass) {        synchronized (lock) {            ListenerBroadcast<T> broadcaster = broadcasters.get(listenerClass);            if (broadcaster == null) {                broadcaster = new ListenerBroadcast<T>(listenerClass);//Add dispatch object into broadcaster's handlers queue.                broadcaster.add(getLogger(listenerClass));                broadcaster.add(getDispatcher(listenerClass));                if (parent != null) {                    broadcaster.add(parent.getDispatcher(listenerClass));                }                broadcasters.put(listenerClass, broadcaster);            }            return broadcaster;        }    }private LoggerDispatch getLogger(Class<?> listenerClass) {        synchronized (lock) {            LoggerDispatch dispatch = loggers.get(listenerClass);            if (dispatch == null) {                dispatch = new LoggerDispatch(listenerClass, parent == null ? null : parent.getLogger(listenerClass));

<span style="white-space:pre"></span>//when called by parent, the dispatch.dispath is null, but the 'allLoggers' is not, so it try to assign a value to dispath.dispatch by calling maybeSetLogger function                for (Object logger : allLoggers) {                    dispatch.maybeSetLogger(logger);                }                loggers.put(listenerClass, dispatch);            }            return dispatch;        }    }    private LoggerDispatch(Class<?> type, LoggerDispatch parentDispatch) {            this.type = type;            this.dispatch = parentDispatch;        }//1.In  org.gradle.initialization DefaultGradleLauncherFactory.java//The constructor of DefaultGradleLauncherFactory    // Register default loggers         ListenerManager listenerManager = sharedServices.get(ListenerManager.class);        buildProgressLogger = new BuildProgressLogger(sharedServices.get(ProgressLoggerFactory.class));//interface 1, 'allListeners' is empty, and only add item to Set<>, do nothing else.        listenerManager.addListener(new BuildProgressFilter(buildProgressLogger));//interface 2, 'allLoggers' is empty, and only add item to Set<>, do nothing else        listenerManager.useLogger(new DependencyResolutionLogger(sharedServices.get(ProgressLoggerFactory.class)));//2. Same package, DefaultGradleLauncherFactory.java//doNewInstance function//小插曲，调用了一下函数 from BuildScopeServies::createListenerManager/*public ListenerManager createChild() {return new DefaultListenerManager(this);}*///Then the 'listenerManager' is a totally new object, //and the one before becomes its 'parent'ListenerManager listenerManager = serviceRegistry.get(ListenerManager.class);        //this hooks up the ListenerManager and LoggingConfigurer so you can call Gradle.addListener() with a StandardOutputListener.//Interface 3, 'broadcasters' map is empty , then new an ListenerBroadcast object 'broadcaster'//In 'getLogger', the 'loggers' is empty, //in new LoggerDispatch, it will call parent.getLogger first (递归), parent's loggers is empty //so parent listenerManager will return a LoggerDispatch object, with 'dispatch' null, and put it into parent's loggers queue.//To son's turn, the new LoggerDispatch will be an object with 'dispatch' point to the object returned from parent.//Parent.loggers.values constains a value of DefaultListenerManager$LoggerDispatch (id=196), its dispatch is null//this.loggers.values constains value of DefaultListenerManager$LoggerDispatch, it's dispatch var member is also a DefaultListenerManager$LoggerDispatch//with id=196, so the parent/child chain is made        loggingManager.addStandardOutputListener(listenerManager.getBroadcaster(StandardOutputListener.class));

执行完

listenerManager.getBroadcaster(StandardOutputListener.class)以后，listenerManager 和它的parent的成员结构大致如下， 数字是调试时候的id