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      1 /*
      2  * Copyright (C) 2019 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License
     15  */
     16 
     17 package com.android.systemui
     18 
     19 import android.util.Log
     20 import androidx.annotation.GuardedBy
     21 import com.android.internal.util.Preconditions
     22 import java.io.FileDescriptor
     23 import java.io.PrintWriter
     24 import java.lang.ref.WeakReference
     25 import javax.inject.Inject
     26 import javax.inject.Singleton
     27 
     28 // TODO: Move all Dumpable dependencies to use DumpController
     29 /**
     30  * Controller that allows any [Dumpable] to subscribe and be dumped along with other SystemUI
     31  * dependencies.
     32  */
     33 @Singleton
     34 class DumpController @Inject constructor() : Dumpable {
     35 
     36     companion object {
     37         private const val TAG = "DumpController"
     38         private const val DEBUG = false
     39     }
     40 
     41     @GuardedBy("listeners")
     42     private val listeners = mutableListOf<WeakReference<Dumpable>>()
     43     val numListeners: Int
     44         get() = listeners.size
     45 
     46     /**
     47      * Adds a [Dumpable] listener to be dumped. It will only be added if it is not already tracked.
     48      *
     49      * @param listener the [Dumpable] to be added
     50      */
     51     fun addListener(listener: Dumpable) {
     52         Preconditions.checkNotNull(listener, "The listener to be added cannot be null")
     53         if (DEBUG) Log.v(TAG, "*** register callback for $listener")
     54         synchronized<Unit>(listeners) {
     55             if (listeners.any { it.get() == listener }) {
     56                 if (DEBUG) {
     57                     Log.e(TAG, "Object tried to add another callback")
     58                 }
     59             } else {
     60                 listeners.add(WeakReference(listener))
     61             }
     62         }
     63     }
     64 
     65     /**
     66      * Removes a listener from the list of elements to be dumped.
     67      *
     68      * @param listener the [Dumpable] to be removed.
     69      */
     70     fun removeListener(listener: Dumpable) {
     71         if (DEBUG) Log.v(TAG, "*** unregister callback for $listener")
     72         synchronized(listeners) {
     73             listeners.removeAll { it.get() == listener || it.get() == null }
     74         }
     75     }
     76 
     77     /**
     78      * Dump all the [Dumpable] registered with the controller
     79      */
     80     override fun dump(fd: FileDescriptor?, pw: PrintWriter, args: Array<String>?) {
     81         pw.println("DumpController state:")
     82         synchronized(listeners) {
     83             listeners.forEach { it.get()?.dump(fd, pw, args) }
     84         }
     85     }
     86 }
     87