MultiProcessDataStoreFactory.kt
/*
* Copyright 2022 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 java.io.File
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.SupervisorJob
public object MultiProcessDataStoreFactory {
/**
* Create an instance of MultiProcessDataStore, which provides cross-process eventual
* consistency. Never create more than one instance of DataStore for a given file in the same
* process; doing so can break all DataStore functionality. You should consider managing your
* DataStore instance for each file as a singleton. If there are multiple DataStores active for
* a given file in the same process, DataStore will throw IllegalStateException when reading or
* updating data. A DataStore is considered active as long as its scope is active. Having
* multiple instances, each for a different file, in the same process is OK.
*
* 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 storage Storage to handle file reads and writes used with DataStore. The type T must
* be immutable. The storage must operate on the same file as the one passed in
* {@link produceFile}.
* @param corruptionHandler The [ReplaceFileCorruptionHandler] 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.
*
* @return a new DataStore instance with the provided configuration
*/
@ExperimentalMultiProcessDataStore
@JvmOverloads // Generate constructors for default params for java users.
public fun <T> create(
storage: Storage<T>,
corruptionHandler: ReplaceFileCorruptionHandler<T>? = null,
migrations: List<DataMigration<T>> = listOf(),
scope: CoroutineScope = CoroutineScope(Dispatchers.IO + SupervisorJob())
): DataStore<T> = DataStoreImpl<T>(
storage = storage,
initTasksList = listOf(DataMigrationInitializer.getInitializer(migrations)),
corruptionHandler = corruptionHandler ?: NoOpCorruptionHandler(),
scope = scope
)
/**
* Create an instance of MultiProcessDataStore, which provides cross-process eventual
* consistency. Never create more than one instance of DataStore for a given file in the same
* process; doing so can break all DataStore functionality. You should consider managing your
* DataStore instance for each file as a singleton. If there are multiple DataStores active for
* a given file in the same process, DataStore will throw IllegalStateException when reading or
* updating data. A DataStore is considered active as long as its scope is active. Having
* multiple instances, each for a different file, in the same process is OK.
*
* 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 {@link androidx.datastore.core.handlers.ReplaceFileCorruptionHandler}
* 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 in the same process.
*
* @return a new DataStore instance with the provided configuration
*/
@ExperimentalMultiProcessDataStore
@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> = DataStoreImpl<T>(
storage = FileStorage(
serializer,
{ MultiProcessCoordinator(scope.coroutineContext, it) },
produceFile
),
initTasksList = listOf(DataMigrationInitializer.getInitializer(migrations)),
corruptionHandler = corruptionHandler ?: NoOpCorruptionHandler(),
scope = scope
)
}