Merge "Removing support for interporcess event from EventBus"

package com.android.systemui.recents.events;

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.content.IntentFilter;

import android.os.Bundle;

import android.os.Handler;

import android.os.Looper;

import android.os.SystemClock;

import android.os.UserHandle;

import android.util.Log;

import android.util.MutableBoolean;

import com.android.systemui.recents.misc.ReferenceCountedTrigger;

import java.io.PrintWriter;

import java.lang.ref.WeakReference;

import java.lang.reflect.Constructor;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.lang.reflect.Modifier;

 * <p>

 * Currently, there is a single EventBus that handles {@link EventBus.Event}s for each subscriber

 * on the main application thread.  Publishers can send() events to synchronously call subscribers

 * of that event, or post() events to be processed in the next run of the {@link Looper}.  In

 * addition, the EventBus supports sending and handling {@link EventBus.InterprocessEvent}s

 * (within the same package) implemented using standard {@link BroadcastReceiver} mechanism.

 * Interprocess events must be posted using postInterprocess() to ensure that it is dispatched

 * correctly across processes.

 * of that event, or post() events to be processed in the next run of the {@link Looper}.

 *

 * <p>

 * Subscribers must be registered with a particular EventBus before they will receive events, and

 * <li>Methods must take one parameter, of class type deriving from {@link EventBus.Event}

 * </ul>

 *

 * <p>

 * Interprocess-Event method signature:<ul>

 * <li>Methods must be public final

 * <li>Methods must return void

 * <li>Methods must be called "onInterprocessBusEvent"

 * <li>Methods must take one parameter, of class type deriving from {@link EventBus.InterprocessEvent}

 * </ul>

 * </p>

 *

 * </p>

 * Each subscriber can be registered with a given priority (default 1), and events will be dispatch

 * in decreasing order of priority.  For subscribers with the same priority, events will be

 * dispatched by latest registration time to earliest.

 *

 * <p>

 * Interprocess events must extend {@link EventBus.InterprocessEvent}, have a constructor which

 * takes a {@link Bundle} and implement toBundle().  This allows us to serialize events to be sent

 * across processes.

 *

 * <p>

 * Caveats:<ul>

 * <li>The EventBus keeps a {@link WeakReference} to the publisher to prevent memory leaks, so

 * there must be another strong reference to the publisher for it to not get garbage-collected and

 * result?

 * </p>

 */

public class EventBus extends BroadcastReceiver {

public class EventBus {

    private static final String TAG = "EventBus";

    private static final boolean DEBUG_TRACE_ALL = false;

        }

    }

    /**

     * An inter-process event super class that allows us to track user state across subscriber

     * invocations.

     */

    public static class InterprocessEvent extends Event {

        private static final String EXTRA_USER = "_user";

        // The user which this event originated from

        public final int user;

        // Only accessible from derived events

        protected InterprocessEvent(int user) {

            this.user = user;

        }

        /**

         * Called from the event bus

         */

        protected InterprocessEvent(Bundle b) {

            user = b.getInt(EXTRA_USER);

        }

        protected Bundle toBundle() {

            Bundle b = new Bundle();

            b.putInt(EXTRA_USER, user);

            return b;

        }

    }

    /**

     * Proguard must also know, and keep, all methods matching this signature.

     *

     * }

     */

    private static final String METHOD_PREFIX = "onBusEvent";

    private static final String INTERPROCESS_METHOD_PREFIX = "onInterprocessBusEvent";

    // Ensures that interprocess events can only be sent from a process holding this permission. */

    private static final String PERMISSION_SELF = "com.android.systemui.permission.SELF";

    // Used for passing event data across process boundaries

    private static final String EXTRA_INTERPROCESS_EVENT_BUNDLE = "interprocess_event_bundle";

    // The default priority of all subscribers

    private static final int DEFAULT_SUBSCRIBER_PRIORITY = 1;

    // The handler to post all events

    private Handler mHandler;

    // Keep track of whether we have registered a broadcast receiver already, so that we can

    // unregister ourselves before re-registering again with a new IntentFilter.

    private boolean mHasRegisteredReceiver;

    /**

     * Map from event class -> event handler list.  Keeps track of the actual mapping from event

     * to subscriber method.

     */

    private HashMap<Class<? extends Object>, ArrayList<EventHandlerMethod>> mSubscriberTypeMap = new HashMap<>();

    /**

     * Map from interprocess event name -> interprocess event class.  Used for mapping the event

     * name after receiving the broadcast, to the event type.  After which a new instance is created

     * and posted in the local process.

     */

    private HashMap<String, Class<? extends InterprocessEvent>> mInterprocessEventNameMap = new HashMap<>();

    /**

     * Set of all currently registered subscribers

     */

     *                   be scanned for appropriate event handler methods.

     */

    public void register(Object subscriber) {

        registerSubscriber(subscriber, DEFAULT_SUBSCRIBER_PRIORITY, null);

        registerSubscriber(subscriber, DEFAULT_SUBSCRIBER_PRIORITY);

    }

    /**

     *                 subscribers

     */

    public void register(Object subscriber, int priority) {

        registerSubscriber(subscriber, priority, null);

    }

    /**

     * Explicitly registers a subscriber to receive interprocess events with the default priority.

     *

     * @param subscriber the subscriber to handle events.  If this is the first instance of the

     *                   subscriber's class type that has been registered, the class's methods will

     *                   be scanned for appropriate event handler methods.

     */

    public void registerInterprocessAsCurrentUser(Context context, Object subscriber) {

        registerInterprocessAsCurrentUser(context, subscriber, DEFAULT_SUBSCRIBER_PRIORITY);

    }

    /**

     * Registers a subscriber to receive interprocess events with the given priority.

     *

     * @param subscriber the subscriber to handle events.  If this is the first instance of the

     *                   subscriber's class type that has been registered, the class's methods will

     *                   be scanned for appropriate event handler methods.

     * @param priority the priority that this subscriber will receive events relative to other

     *                 subscribers

     */

    public void registerInterprocessAsCurrentUser(Context context, Object subscriber, int priority) {

        if (DEBUG_TRACE_ALL) {

            logWithPid("registerInterprocessAsCurrentUser(" + subscriber.getClass().getSimpleName() + ")");

        }

        // Register the subscriber normally, and update the broadcast receiver filter if this is

        // a new subscriber type with interprocess events

        MutableBoolean hasInterprocessEventsChanged = new MutableBoolean(false);

        registerSubscriber(subscriber, priority, hasInterprocessEventsChanged);

        if (DEBUG_TRACE_ALL) {

            logWithPid("hasInterprocessEventsChanged: " + hasInterprocessEventsChanged.value);

        }

        if (hasInterprocessEventsChanged.value) {

            registerReceiverForInterprocessEvents(context);

        }

        registerSubscriber(subscriber, priority);

    }

    /**

        }

    }

    /**

     * Explicit unregistration for interprocess event subscribers.  This actually behaves exactly

     * the same as unregister() since we also do not want to stop listening for specific

     * inter-process messages in case new instances of that subscriber is registered.

     */

    public void unregisterInterprocess(Context context, Object subscriber) {

        if (DEBUG_TRACE_ALL) {

            logWithPid("unregisterInterprocess()");

        }

        unregister(subscriber);

    }

    /**

     * Sends an event to the subscribers of the given event type immediately.  This can only be

     * called from the same thread as the EventBus's looper thread (for the default EventBus, this

        }

    }

    /** Prevent post()ing an InterprocessEvent */

    @Deprecated

    public void post(InterprocessEvent event) {

        throw new RuntimeException("Not supported, use postInterprocess");

    }

    /** Prevent send()ing an InterprocessEvent */

    @Deprecated

    public void send(InterprocessEvent event) {

        throw new RuntimeException("Not supported, use postInterprocess");

    }

    /**

     * Posts an interprocess event.

     */

    public void postInterprocess(Context context, final InterprocessEvent event) {

        if (DEBUG_TRACE_ALL) {

            logWithPid("postInterprocess(" + event.getClass().getSimpleName() + ")");

        }

        String eventType = event.getClass().getName();

        Bundle eventBundle = event.toBundle();

        Intent intent = new Intent(eventType);

        intent.setPackage(context.getPackageName());

        intent.putExtra(EXTRA_INTERPROCESS_EVENT_BUNDLE, eventBundle);

        intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT |

                Intent.FLAG_RECEIVER_FOREGROUND);

        context.sendBroadcastAsUser(intent, UserHandle.ALL);

    }

    /**

     * Receiver for interprocess events.

     */

    @Override

    public void onReceive(Context context, Intent intent) {

        if (DEBUG_TRACE_ALL) {

            logWithPid("onReceive(" + intent.getAction() + ", user " + UserHandle.myUserId() + ")");

        }

        Bundle eventBundle = intent.getBundleExtra(EXTRA_INTERPROCESS_EVENT_BUNDLE);

        Class<? extends InterprocessEvent> eventType = mInterprocessEventNameMap.get(intent.getAction());

        try {

            Constructor<? extends InterprocessEvent> ctor = eventType.getConstructor(Bundle.class);

            send((Event) ctor.newInstance(eventBundle));

        } catch (NoSuchMethodException|

                InvocationTargetException|

                InstantiationException|

                IllegalAccessException e) {

            Log.e(TAG, "Failed to create InterprocessEvent", e.getCause());

        }

    }

    /**

     * @return a dump of the current state of the EventBus

     */

    /**

     * Registers a new subscriber.

     */

    private void registerSubscriber(Object subscriber, int priority,

            MutableBoolean hasInterprocessEventsChangedOut) {

    private void registerSubscriber(Object subscriber, int priority) {

        // Fail immediately if we are being called from the non-main thread

        long callingThreadId = Thread.currentThread().getId();

        if (callingThreadId != mHandler.getLooper().getThread().getId()) {

        }

        // Find all the valid event bus handler methods of the subscriber

        MutableBoolean isInterprocessEvent = new MutableBoolean(false);

        Method[] methods = subscriberType.getDeclaredMethods();

        for (Method m : methods) {

            Class<?>[] parameterTypes = m.getParameterTypes();

            isInterprocessEvent.value = false;

            if (isValidEventBusHandlerMethod(m, parameterTypes, isInterprocessEvent)) {

            if (isValidEventBusHandlerMethod(m, parameterTypes)) {

                Class<? extends Event> eventType = (Class<? extends Event>) parameterTypes[0];

                ArrayList<EventHandler> eventTypeHandlers = mEventTypeMap.get(eventType);

                if (eventTypeHandlers == null) {

                    eventTypeHandlers = new ArrayList<>();

                    mEventTypeMap.put(eventType, eventTypeHandlers);

                }

                if (isInterprocessEvent.value) {

                    try {

                        // Enforce that the event must have a Bundle constructor

                        eventType.getConstructor(Bundle.class);

                        mInterprocessEventNameMap.put(eventType.getName(),

                                (Class<? extends InterprocessEvent>) eventType);

                        if (hasInterprocessEventsChangedOut != null) {

                            hasInterprocessEventsChangedOut.value = true;

                        }

                    } catch (NoSuchMethodException e) {

                        throw new RuntimeException("Expected InterprocessEvent to have a Bundle constructor");

                    }

                }

                EventHandlerMethod method = new EventHandlerMethod(m, eventType);

                EventHandler handler = new EventHandler(sub, method, priority);

                eventTypeHandlers.add(handler);

                if (DEBUG_TRACE_ALL) {

                    logWithPid("  * Method: " + m.getName() +

                            " event: " + parameterTypes[0].getSimpleName() +

                            " interprocess? " + isInterprocessEvent.value);

                            " event: " + parameterTypes[0].getSimpleName());

                }

            }

        }

            final EventHandler eventHandler = eventHandlers.get(i);

            if (eventHandler.subscriber.getReference() != null) {

                if (event.requiresPost) {

                    mHandler.post(new Runnable() {

                        @Override

                        public void run() {

                            processEvent(eventHandler, event);

                        }

                    });

                    mHandler.post(() -> processEvent(eventHandler, event));

                    hasPostedEvent = true;

                } else {

                    processEvent(eventHandler, event);

        // Clean up after this event, deferring until all subscribers have been called

        if (hasPostedEvent) {

            mHandler.post(new Runnable() {

                @Override

                public void run() {

                    event.onPostDispatch();

                }

            });

            mHandler.post(event::onPostDispatch);

        } else {

            event.onPostDispatch();

        }

        }

    }

    /**

     * Re-registers the broadcast receiver for any new messages that we want to listen for.

     */

    private void registerReceiverForInterprocessEvents(Context context) {

        if (DEBUG_TRACE_ALL) {

            logWithPid("registerReceiverForInterprocessEvents()");

        }

        // Rebuild the receiver filter with the new interprocess events

        IntentFilter filter = new IntentFilter();

        for (String eventName : mInterprocessEventNameMap.keySet()) {

            filter.addAction(eventName);

            if (DEBUG_TRACE_ALL) {

                logWithPid("  filter: " + eventName);

            }

        }

        // Re-register the receiver with the new filter

        if (mHasRegisteredReceiver) {

            context.unregisterReceiver(this);

        }

        context.registerReceiverAsUser(this, UserHandle.ALL, filter, PERMISSION_SELF, mHandler);

        mHasRegisteredReceiver = true;

    }

    /**

     * Returns whether this subscriber is currently registered.  If {@param removeFoundSubscriber}

     * is true, then remove the subscriber before returning.

    /**

     * @return whether {@param method} is a valid (normal or interprocess) event bus handler method

     */

    private boolean isValidEventBusHandlerMethod(Method method, Class<?>[] parameterTypes,

            MutableBoolean isInterprocessEventOut) {

    private boolean isValidEventBusHandlerMethod(Method method, Class<?>[] parameterTypes) {

        int modifiers = method.getModifiers();

        if (Modifier.isPublic(modifiers) &&

                Modifier.isFinal(modifiers) &&

                method.getReturnType().equals(Void.TYPE) &&

                parameterTypes.length == 1) {

            if (EventBus.InterprocessEvent.class.isAssignableFrom(parameterTypes[0]) &&

                    method.getName().startsWith(INTERPROCESS_METHOD_PREFIX)) {

                isInterprocessEventOut.value = true;

                return true;

            } else if (EventBus.Event.class.isAssignableFrom(parameterTypes[0]) &&

            if (EventBus.Event.class.isAssignableFrom(parameterTypes[0]) &&

                            method.getName().startsWith(METHOD_PREFIX)) {

                isInterprocessEventOut.value = false;

                return true;

            } else {

                if (DEBUG_TRACE_ALL) {

                    if (!EventBus.Event.class.isAssignableFrom(parameterTypes[0])) {

                        logWithPid("  Expected method take an Event-based parameter: " + method.getName());

                    } else if (!method.getName().startsWith(INTERPROCESS_METHOD_PREFIX) &&

                            !method.getName().startsWith(METHOD_PREFIX)) {

                        logWithPid("  Expected method start with method prefix: " + method.getName());

                    }

                }

            }