DataStoreFactory.kt
/*
* Copyright 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.datastore.core
import androidx.datastore.core.handlers.NoOpCorruptionHandler
import androidx.datastore.core.handlers.ReplaceFileCorruptionHandler
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.SupervisorJob
import java.io.File
/**
* Public factory for creating DataStore instances.
*/
public object DataStoreFactory {
/**
* Create an instance of SingleProcessDataStore. Never create more than one instance of
* DataStore for a given file; doing so can break all DataStore functionality. You should
* consider managing your DataStore instance as a singleton.
*
* T is the type DataStore acts on. The type T must be immutable. Mutating a type used in
* DataStore invalidates any guarantees that DataStore provides and will result in
* potentially serious, hard-to-catch bugs. We strongly recommend using protocol buffers:
* https://developers.google.com/protocol-buffers/docs/javatutorial - which provides
* immutability guarantees, a simple API and efficient serialization.
*
* @param serializer Serializer for the type T used with DataStore. The type T must be immutable.
* @param corruptionHandler The corruptionHandler is invoked if DataStore encounters a
* [CorruptionException] when attempting to read data. CorruptionExceptions are thrown by
* serializers when data can not be de-serialized.
* @param migrations Migrations are run before any access to data can occur. Migrations must
* be idempotent.
* @param scope The scope in which IO operations and transform functions will execute.
* @param produceFile Function which returns the file that the new DataStore will act on. The
* function must return the same path every time. No two instances of DataStore should act on
* the same file at the same time.
*
* @return a new DataStore instance with the provided configuration
*/
@JvmOverloads // Generate constructors for default params for java users.
public fun <T> create(
serializer: Serializer<T>,
corruptionHandler: ReplaceFileCorruptionHandler<T>? = null,
migrations: List<DataMigration<T>> = listOf(),
scope: CoroutineScope = CoroutineScope(Dispatchers.IO + SupervisorJob()),
produceFile: () -> File
): DataStore<T> =
SingleProcessDataStore(
produceFile = produceFile,
serializer = serializer,
corruptionHandler = corruptionHandler ?: NoOpCorruptionHandler(),
initTasksList = listOf(DataMigrationInitializer.getInitializer(migrations)),
scope = scope
)
}