1 /*
2  * Copyright 2022 The Android Open Source Project
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 androidx.datastore.core
18 
19 import kotlin.coroutines.CoroutineContext
20 import kotlinx.coroutines.CompletableDeferred
21 
22 /** The actions for the actor. */
23 internal sealed class Message<T> {
24     abstract val lastState: State<T>?
25 
26     /**
27      * Represents a read operation. If the data is already cached, this is a no-op. If data has not
28      * been cached, it triggers a new read to the specified dataChannel.
29      */
30     class Read<T>(override val lastState: State<T>?) : Message<T>()
31 
32     /** Represents an update operation. */
33     class Update<T>(
34         val transform: suspend (t: T) -> T,
35         /** Used to signal (un)successful completion of the update to the caller. */
36         val ack: CompletableDeferred<T>,
37         override val lastState: State<T>?,
38         val callerContext: CoroutineContext
39     ) : Message<T>()
40 }
41