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      */
addListenernull51     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      */
removeListenernull70     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      */
dumpnull80     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