ThreadSafeInvalidationObserver.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.room.paging.util
import androidx.annotation.RestrictTo
import androidx.room.InvalidationTracker
import androidx.room.RoomDatabase
import java.util.concurrent.atomic.AtomicBoolean
@Suppress("UNCHECKED_CAST")
@RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
class ThreadSafeInvalidationObserver(
tables: Array<out String>,
val onInvalidated: () -> Unit,
) : InvalidationTracker.Observer(tables = tables as Array<String>) {
private val registered: AtomicBoolean = AtomicBoolean(false)
override fun onInvalidated(tables: Set<String>) {
onInvalidated()
}
fun registerIfNecessary(db: RoomDatabase) {
if (registered.compareAndSet(false, true)) {
db.invalidationTracker.addWeakObserver(this)
}
}
}