mirror of https://github.com/M66B/FairEmail.git
65 lines
1.9 KiB
Java
65 lines
1.9 KiB
Java
/*
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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 androidx.annotation.NonNull;
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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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* <p>
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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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class TransactionExecutor implements Executor {
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private final Executor mExecutor;
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private final ArrayDeque<Runnable> mTasks = new ArrayDeque<>();
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private Runnable mActive;
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TransactionExecutor(@NonNull Executor executor) {
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mExecutor = executor;
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}
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@Override
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public synchronized void execute(final Runnable command) {
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mTasks.offer(new Runnable() {
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@Override
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public void run() {
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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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});
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if (mActive == null) {
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scheduleNext();
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}
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}
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@SuppressWarnings("WeakerAccess")
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synchronized void scheduleNext() {
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if ((mActive = mTasks.poll()) != null) {
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mExecutor.execute(mActive);
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}
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}
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}
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