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| 1 | +/* |
| 2 | + * Copyright 2025 Google LLC |
| 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.google.firebase.datastore |
| 18 | + |
| 19 | +import android.content.Context |
| 20 | +import androidx.datastore.core.DataStore |
| 21 | +import androidx.datastore.preferences.SharedPreferencesMigration |
| 22 | +import androidx.datastore.preferences.core.MutablePreferences |
| 23 | +import androidx.datastore.preferences.core.Preferences |
| 24 | +import androidx.datastore.preferences.core.edit |
| 25 | +import androidx.datastore.preferences.preferencesDataStore |
| 26 | +import com.google.firebase.annotations.concurrent.Background |
| 27 | +import kotlinx.coroutines.flow.firstOrNull |
| 28 | +import kotlinx.coroutines.runBlocking |
| 29 | + |
| 30 | +/** |
| 31 | + * Wrapper around [DataStore] for easier migration from `SharedPreferences` in Java code. |
| 32 | + * |
| 33 | + * Automatically migrates data from any `SharedPreferences` that share the same context and name. |
| 34 | + * |
| 35 | + * There should only ever be _one_ instance of this class per context and name variant. |
| 36 | + * |
| 37 | + * Note that most of the methods in this class **block** on the _current_ thread, as to help keep |
| 38 | + * parity with existing Java code. Typically, you'd want to dispatch this work to another thread |
| 39 | + * like [@Background][Background]. |
| 40 | + * |
| 41 | + * > Do **NOT** use this _unless_ you're bridging Java code. If you're writing new code, or your |
| 42 | + * code is in Kotlin, then you should create your own singleton that uses [DataStore] directly. |
| 43 | + * |
| 44 | + * Example: |
| 45 | + * ```java |
| 46 | + * DataStorage heartBeatStorage = new DataStorage(applicationContext, "FirebaseHeartBeat"); |
| 47 | + * ``` |
| 48 | + * |
| 49 | + * @property context The [Context] that this data will be saved under. |
| 50 | + * @property name What the storage file should be named. |
| 51 | + * |
| 52 | + * @hide |
| 53 | + */ |
| 54 | +class DataStorage(val context: Context, val name: String) { |
| 55 | + /** |
| 56 | + * Used to ensure that there's only ever one call to [editSync] per thread; as to avoid deadlocks. |
| 57 | + */ |
| 58 | + private val editLock = ThreadLocal<Boolean>() |
| 59 | + |
| 60 | + private val Context.dataStore: DataStore<Preferences> by |
| 61 | + preferencesDataStore( |
| 62 | + name = name, |
| 63 | + produceMigrations = { listOf(SharedPreferencesMigration(it, name)) } |
| 64 | + ) |
| 65 | + |
| 66 | + private val dataStore = context.dataStore |
| 67 | + |
| 68 | + /** |
| 69 | + * Get data from the datastore _synchronously_. |
| 70 | + * |
| 71 | + * Note that if the key is _not_ in the datastore, while the [defaultValue] will be returned |
| 72 | + * instead- it will **not** be saved to the datastore; you'll have to manually do that. |
| 73 | + * |
| 74 | + * Blocks on the currently running thread. |
| 75 | + * |
| 76 | + * Example: |
| 77 | + * ```java |
| 78 | + * Preferences.Key<Long> fireCountKey = PreferencesKeys.longKey("fire-count"); |
| 79 | + * assert dataStore.get(fireCountKey, 0L) == 0L; |
| 80 | + * |
| 81 | + * dataStore.putSync(fireCountKey, 102L); |
| 82 | + * assert dataStore.get(fireCountKey, 0L) == 102L; |
| 83 | + * ``` |
| 84 | + * |
| 85 | + * @param key The typed key of the entry to get data for. |
| 86 | + * @param defaultValue A value to default to, if the key isn't found. |
| 87 | + * |
| 88 | + * @see Preferences.getOrDefault |
| 89 | + */ |
| 90 | + fun <T> getSync(key: Preferences.Key<T>, defaultValue: T): T = runBlocking { |
| 91 | + dataStore.data.firstOrNull()?.get(key) ?: defaultValue |
| 92 | + } |
| 93 | + |
| 94 | + /** |
| 95 | + * Checks if a key is present in the datastore _synchronously_. |
| 96 | + * |
| 97 | + * Blocks on the currently running thread. |
| 98 | + * |
| 99 | + * Example: |
| 100 | + * ```java |
| 101 | + * Preferences.Key<Long> fireCountKey = PreferencesKeys.longKey("fire-count"); |
| 102 | + * assert !dataStore.contains(fireCountKey); |
| 103 | + * |
| 104 | + * dataStore.putSync(fireCountKey, 102L); |
| 105 | + * assert dataStore.contains(fireCountKey); |
| 106 | + * ``` |
| 107 | + * |
| 108 | + * @param key The typed key of the entry to find. |
| 109 | + */ |
| 110 | + fun <T> contains(key: Preferences.Key<T>): Boolean = runBlocking { |
| 111 | + dataStore.data.firstOrNull()?.contains(key) ?: false |
| 112 | + } |
| 113 | + |
| 114 | + /** |
| 115 | + * Sets and saves data in the datastore _synchronously_. |
| 116 | + * |
| 117 | + * Existing values will be overwritten. |
| 118 | + * |
| 119 | + * Blocks on the currently running thread. |
| 120 | + * |
| 121 | + * Example: |
| 122 | + * ```java |
| 123 | + * dataStore.putSync(PreferencesKeys.longKey("fire-count"), 102L); |
| 124 | + * ``` |
| 125 | + * |
| 126 | + * @param key The typed key of the entry to save the data under. |
| 127 | + * @param value The data to save. |
| 128 | + * |
| 129 | + * @return The [Preferences] object that the data was saved under. |
| 130 | + */ |
| 131 | + fun <T> putSync(key: Preferences.Key<T>, value: T): Preferences = runBlocking { |
| 132 | + dataStore.edit { it[key] = value } |
| 133 | + } |
| 134 | + |
| 135 | + /** |
| 136 | + * Gets all data in the datastore _synchronously_. |
| 137 | + * |
| 138 | + * Blocks on the currently running thread. |
| 139 | + * |
| 140 | + * Example: |
| 141 | + * ```java |
| 142 | + * ArrayList<String> allDates = new ArrayList<>(); |
| 143 | + * |
| 144 | + * for (Map.Entry<Preferences.Key<?>, Object> entry : dataStore.getAllSync().entrySet()) { |
| 145 | + * if (entry.getValue() instanceof Set) { |
| 146 | + * Set<String> dates = new HashSet<>((Set<String>) entry.getValue()); |
| 147 | + * if (!dates.isEmpty()) { |
| 148 | + * allDates.add(new ArrayList<>(dates)); |
| 149 | + * } |
| 150 | + * } |
| 151 | + * } |
| 152 | + * ``` |
| 153 | + * |
| 154 | + * @return An _immutable_ map of data currently present in the datastore. |
| 155 | + */ |
| 156 | + fun getAllSync(): Map<Preferences.Key<*>, Any> = runBlocking { |
| 157 | + dataStore.data.firstOrNull()?.asMap() ?: emptyMap() |
| 158 | + } |
| 159 | + |
| 160 | + /** |
| 161 | + * Transactionally edit data in the datastore _synchronously_. |
| 162 | + * |
| 163 | + * Edits made within the [transform] callback will be saved (committed) all at once once the |
| 164 | + * [transform] block exits. |
| 165 | + * |
| 166 | + * Because of the blocking nature of this function, you should _never_ call [editSync] within an |
| 167 | + * already running [transform] block. Since this can cause a deadlock, [editSync] will instead |
| 168 | + * throw an exception if it's caught. |
| 169 | + * |
| 170 | + * Blocks on the currently running thread. |
| 171 | + * |
| 172 | + * Example: |
| 173 | + * ```java |
| 174 | + * dataStore.editSync((pref) -> { |
| 175 | + * Long heartBeatCount = pref.get(HEART_BEAT_COUNT_TAG); |
| 176 | + * if (heartBeatCount == null || heartBeatCount > 30) { |
| 177 | + * heartBeatCount = 0L; |
| 178 | + * } |
| 179 | + * pref.set(HEART_BEAT_COUNT_TAG, heartBeatCount); |
| 180 | + * pref.set(LAST_STORED_DATE, "1970-0-1"); |
| 181 | + * |
| 182 | + * return null; |
| 183 | + * }); |
| 184 | + * ``` |
| 185 | + * |
| 186 | + * @param transform A callback to invoke with the [MutablePreferences] object. |
| 187 | + * |
| 188 | + * @return The [Preferences] object that the data was saved under. |
| 189 | + * @throws IllegalStateException If you attempt to call [editSync] within another [transform] |
| 190 | + * block. |
| 191 | + * |
| 192 | + * @see Preferences.getOrDefault |
| 193 | + */ |
| 194 | + fun editSync(transform: (MutablePreferences) -> Unit): Preferences = runBlocking { |
| 195 | + if (editLock.get() == true) { |
| 196 | + throw IllegalStateException( |
| 197 | + """ |
| 198 | + Don't call DataStorage.edit() from within an existing edit() callback. |
| 199 | + This causes deadlocks, and is generally indicative of a code smell. |
| 200 | + Instead, either pass around the initial `MutablePreferences` instance, or don't do everything in a single callback. |
| 201 | + """ |
| 202 | + .trimIndent() |
| 203 | + ) |
| 204 | + } |
| 205 | + editLock.set(true) |
| 206 | + try { |
| 207 | + dataStore.edit { transform(it) } |
| 208 | + } finally { |
| 209 | + editLock.set(false) |
| 210 | + } |
| 211 | + } |
| 212 | +} |
| 213 | + |
| 214 | +/** |
| 215 | + * Helper method for getting the value out of a [Preferences] object if it exists, else falling back |
| 216 | + * to the default value. |
| 217 | + * |
| 218 | + * This is primarily useful when working with an instance of [MutablePreferences] |
| 219 | + * - like when working within an [DataStorage.editSync] callback. |
| 220 | + * |
| 221 | + * Example: |
| 222 | + * ```java |
| 223 | + * dataStore.editSync((pref) -> { |
| 224 | + * long heartBeatCount = DataStoreKt.getOrDefault(pref, HEART_BEAT_COUNT_TAG, 0L); |
| 225 | + * heartBeatCount+=1; |
| 226 | + * pref.set(HEART_BEAT_COUNT_TAG, heartBeatCount); |
| 227 | + * |
| 228 | + * return null; |
| 229 | + * }); |
| 230 | + * ``` |
| 231 | + * |
| 232 | + * @param key The typed key of the entry to get data for. |
| 233 | + * @param defaultValue A value to default to, if the key isn't found. |
| 234 | + */ |
| 235 | +fun <T> Preferences.getOrDefault(key: Preferences.Key<T>, defaultValue: T) = |
| 236 | + get(key) ?: defaultValue |
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