mirror of https://github.com/M66B/FairEmail.git
55 lines
1.7 KiB
Kotlin
55 lines
1.7 KiB
Kotlin
/*
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* Copyright 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package androidx.room
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import java.util.ArrayDeque
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import java.util.concurrent.Executor
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/**
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* Executor wrapper for performing database transactions serially.
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*
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* Since database transactions are exclusive, this executor ensures that transactions are performed
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* in-order and one at a time, preventing threads from blocking each other when multiple concurrent
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* transactions are attempted.
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*/
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internal class TransactionExecutor(private val executor: Executor) : Executor {
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private val tasks = ArrayDeque<Runnable>()
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private var active: Runnable? = null
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private val syncLock = Any()
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override fun execute(command: Runnable) {
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synchronized(syncLock) {
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tasks.offer(Runnable {
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try {
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command.run()
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} finally {
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scheduleNext()
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}
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})
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if (active == null) {
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scheduleNext()
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}
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}
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}
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fun scheduleNext() {
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synchronized(syncLock) {
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if (tasks.poll().also { active = it } != null) {
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executor.execute(active)
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}
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}
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}
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}
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