1 /* 2 * Copyright (C) 2017 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 package com.android.documentsui; 17 18 import static com.android.documentsui.base.SharedMinimal.DEBUG; 19 20 import android.util.Log; 21 22 import androidx.annotation.GuardedBy; 23 import androidx.annotation.Nullable; 24 import androidx.recyclerview.selection.OperationMonitor; 25 26 /** 27 * ContentLock provides a mechanism to block content from reloading while selection 28 * activities like gesture and band selection are active. Clients using live data 29 * (data loaded, for example by a {@link Loader}), should route calls to load 30 * content through this lock using {@link ContentLock#runWhenUnlocked(Runnable)}. 31 */ 32 public final class ContentLock { 33 34 private static final String TAG = "ContentLock"; 35 36 private final OperationMonitor mMonitor = new OperationMonitor(); 37 38 @GuardedBy("this") 39 private @Nullable Runnable mCallback; 40 ContentLock()41 public ContentLock() { 42 mMonitor.addListener(() -> { 43 if (DEBUG) { 44 Log.d(TAG, "monitor listener, is locked : " + isLocked()); 45 } 46 if (!isLocked()) { 47 synchronized (this) { 48 final Runnable callback = mCallback; 49 if (callback != null) { 50 callback.run(); 51 mCallback = null; 52 } 53 } 54 } 55 }); 56 } 57 getMonitor()58 public OperationMonitor getMonitor() { 59 return mMonitor; 60 } 61 62 /** 63 * Returns true if locked. 64 */ isLocked()65 private boolean isLocked() { 66 return mMonitor.isStarted(); 67 } 68 69 /** 70 * Attempts to run the given Runnable if not-locked, or else the Runnable is set to be ran next 71 * (replacing any previous set Runnables). 72 */ runWhenUnlocked(Runnable runnable)73 public synchronized void runWhenUnlocked(Runnable runnable) { 74 if (DEBUG) { 75 Log.d(TAG, "run when unlock, is locked : " + isLocked()); 76 } 77 if (!isLocked()) { 78 runnable.run(); 79 } else { 80 mCallback = runnable; 81 } 82 } 83 } 84