SingleProcessCoordinator.kt
/*
* Copyright 2023 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 kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.flow
import kotlinx.coroutines.sync.Mutex
import kotlinx.coroutines.sync.withLock
/**
* SingleProcessCoordinator does coordination within a single process. It is used as the default
* [InterProcessCoordinator] immplementation unless otherwise specified.
*/
internal class SingleProcessCoordinator() : InterProcessCoordinator {
private val mutex = Mutex()
private val version = AtomicInt(0)
override val updateNotifications: Flow<Unit> = flow {}
// run block with the exclusive lock
override suspend fun <T> lock(block: suspend () -> T): T {
return mutex.withLock {
block()
}
}
// run block with an attempt to get the exclusive lock, still run even if
// attempt fails. Pass a boolean to indicate if the attempt succeeds.
override suspend fun <T> tryLock(block: suspend (Boolean) -> T): T {
return mutex.withTryLock {
block(it)
}
}
// get the current version
override suspend fun getVersion(): Int = version.get()
// increment version and return the new one
override suspend fun incrementAndGetVersion(): Int = version.incrementAndGet()
}