1 /* 2 * Copyright (C) 2015 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 android.content.res; 18 19 import android.annotation.NonNull; 20 import android.annotation.Nullable; 21 import android.content.pm.ActivityInfo.Config; 22 import android.content.res.Resources.Theme; 23 import android.content.res.Resources.ThemeKey; 24 import android.util.LongSparseArray; 25 import android.util.ArrayMap; 26 27 import java.lang.ref.WeakReference; 28 29 /** 30 * Data structure used for caching data against themes. 31 * 32 * @param <T> type of data to cache 33 */ 34 abstract class ThemedResourceCache<T> { 35 private ArrayMap<ThemeKey, LongSparseArray<WeakReference<T>>> mThemedEntries; 36 private LongSparseArray<WeakReference<T>> mUnthemedEntries; 37 private LongSparseArray<WeakReference<T>> mNullThemedEntries; 38 39 /** 40 * Adds a new theme-dependent entry to the cache. 41 * 42 * @param key a key that uniquely identifies the entry 43 * @param theme the theme against which this entry was inflated, or 44 * {@code null} if the entry has no theme applied 45 * @param entry the entry to cache 46 */ 47 public void put(long key, @Nullable Theme theme, @NonNull T entry) { 48 put(key, theme, entry, true); 49 } 50 51 /** 52 * Adds a new entry to the cache. 53 * 54 * @param key a key that uniquely identifies the entry 55 * @param theme the theme against which this entry was inflated, or 56 * {@code null} if the entry has no theme applied 57 * @param entry the entry to cache 58 * @param usesTheme {@code true} if the entry is affected theme changes, 59 * {@code false} otherwise 60 */ 61 public void put(long key, @Nullable Theme theme, @NonNull T entry, boolean usesTheme) { 62 if (entry == null) { 63 return; 64 } 65 66 synchronized (this) { 67 final LongSparseArray<WeakReference<T>> entries; 68 if (!usesTheme) { 69 entries = getUnthemedLocked(true); 70 } else { 71 entries = getThemedLocked(theme, true); 72 } 73 if (entries != null) { 74 entries.put(key, new WeakReference<>(entry)); 75 } 76 } 77 } 78 79 /** 80 * Returns an entry from the cache. 81 * 82 * @param key a key that uniquely identifies the entry 83 * @param theme the theme where the entry will be used 84 * @return a cached entry, or {@code null} if not in the cache 85 */ 86 @Nullable 87 public T get(long key, @Nullable Theme theme) { 88 // The themed (includes null-themed) and unthemed caches are mutually 89 // exclusive, so we'll give priority to whichever one we think we'll 90 // hit first. Since most of the framework drawables are themed, that's 91 // probably going to be the themed cache. 92 synchronized (this) { 93 final LongSparseArray<WeakReference<T>> themedEntries = getThemedLocked(theme, false); 94 if (themedEntries != null) { 95 final WeakReference<T> themedEntry = themedEntries.get(key); 96 if (themedEntry != null) { 97 return themedEntry.get(); 98 } 99 } 100 101 final LongSparseArray<WeakReference<T>> unthemedEntries = getUnthemedLocked(false); 102 if (unthemedEntries != null) { 103 final WeakReference<T> unthemedEntry = unthemedEntries.get(key); 104 if (unthemedEntry != null) { 105 return unthemedEntry.get(); 106 } 107 } 108 } 109 110 return null; 111 } 112 113 /** 114 * Prunes cache entries that have been invalidated by a configuration 115 * change. 116 * 117 * @param configChanges a bitmask of configuration changes 118 */ 119 public void onConfigurationChange(@Config int configChanges) { 120 prune(configChanges); 121 } 122 123 /** 124 * Returns whether a cached entry has been invalidated by a configuration 125 * change. 126 * 127 * @param entry a cached entry 128 * @param configChanges a non-zero bitmask of configuration changes 129 * @return {@code true} if the entry is invalid, {@code false} otherwise 130 */ 131 protected abstract boolean shouldInvalidateEntry(@NonNull T entry, int configChanges); 132 133 /** 134 * Returns the cached data for the specified theme, optionally creating a 135 * new entry if one does not already exist. 136 * 137 * @param t the theme for which to return cached data 138 * @param create {@code true} to create an entry if one does not already 139 * exist, {@code false} otherwise 140 * @return the cached data for the theme, or {@code null} if the cache is 141 * empty and {@code create} was {@code false} 142 */ 143 @Nullable 144 private LongSparseArray<WeakReference<T>> getThemedLocked(@Nullable Theme t, boolean create) { 145 if (t == null) { 146 if (mNullThemedEntries == null && create) { 147 mNullThemedEntries = new LongSparseArray<>(1); 148 } 149 return mNullThemedEntries; 150 } 151 152 if (mThemedEntries == null) { 153 if (create) { 154 mThemedEntries = new ArrayMap<>(1); 155 } else { 156 return null; 157 } 158 } 159 160 final ThemeKey key = t.getKey(); 161 LongSparseArray<WeakReference<T>> cache = mThemedEntries.get(key); 162 if (cache == null && create) { 163 cache = new LongSparseArray<>(1); 164 165 final ThemeKey keyClone = key.clone(); 166 mThemedEntries.put(keyClone, cache); 167 } 168 169 return cache; 170 } 171 172 /** 173 * Returns the theme-agnostic cached data. 174 * 175 * @param create {@code true} to create an entry if one does not already 176 * exist, {@code false} otherwise 177 * @return the theme-agnostic cached data, or {@code null} if the cache is 178 * empty and {@code create} was {@code false} 179 */ 180 @Nullable 181 private LongSparseArray<WeakReference<T>> getUnthemedLocked(boolean create) { 182 if (mUnthemedEntries == null && create) { 183 mUnthemedEntries = new LongSparseArray<>(1); 184 } 185 return mUnthemedEntries; 186 } 187 188 /** 189 * Prunes cache entries affected by configuration changes or where weak 190 * references have expired. 191 * 192 * @param configChanges a bitmask of configuration changes, or {@code 0} to 193 * simply prune missing weak references 194 * @return {@code true} if the cache is completely empty after pruning 195 */ 196 private boolean prune(@Config int configChanges) { 197 synchronized (this) { 198 if (mThemedEntries != null) { 199 for (int i = mThemedEntries.size() - 1; i >= 0; i--) { 200 if (pruneEntriesLocked(mThemedEntries.valueAt(i), configChanges)) { 201 mThemedEntries.removeAt(i); 202 } 203 } 204 } 205 206 pruneEntriesLocked(mNullThemedEntries, configChanges); 207 pruneEntriesLocked(mUnthemedEntries, configChanges); 208 209 return mThemedEntries == null && mNullThemedEntries == null 210 && mUnthemedEntries == null; 211 } 212 } 213 214 private boolean pruneEntriesLocked(@Nullable LongSparseArray<WeakReference<T>> entries, 215 @Config int configChanges) { 216 if (entries == null) { 217 return true; 218 } 219 220 for (int i = entries.size() - 1; i >= 0; i--) { 221 final WeakReference<T> ref = entries.valueAt(i); 222 if (ref == null || pruneEntryLocked(ref.get(), configChanges)) { 223 entries.removeAt(i); 224 } 225 } 226 227 return entries.size() == 0; 228 } 229 230 private boolean pruneEntryLocked(@Nullable T entry, @Config int configChanges) { 231 return entry == null || (configChanges != 0 232 && shouldInvalidateEntry(entry, configChanges)); 233 } 234 } 235
