mirror of
https://github.com/Tencent/MMKV.git
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guoling
100 lines
2.6 KiB
C++
100 lines
2.6 KiB
C++
/*
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* Tencent is pleased to support the open source community by making
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* MMKV available.
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*
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* Copyright (C) 2019 THL A29 Limited, a Tencent company.
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* All rights reserved.
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*
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* Licensed under the BSD 3-Clause License (the "License"); you may not use
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* this file except in compliance with the License. You may obtain a copy of
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* the License at
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*
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* https://opensource.org/licenses/BSD-3-Clause
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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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#include "ThreadLock.h"
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#if !(MMKV_USING_PTHREAD)
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# include "MMKVLog.h"
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# include <atomic>
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# include <cassert>
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namespace mmkv {
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ThreadLock::ThreadLock() : m_lock{0} {
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}
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ThreadLock::~ThreadLock() {
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while (m_lockCount > 0) {
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LeaveCriticalSection(&m_lock);
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--m_lockCount;
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}
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DeleteCriticalSection(&m_lock);
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}
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void ThreadLock::initialize() {
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// TODO: a better spin count?
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if (!InitializeCriticalSectionAndSpinCount(&m_lock, 1024)) {
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MMKVError("fail to init critical section:%d", GetLastError());
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}
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}
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void ThreadLock::lock() {
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EnterCriticalSection(&m_lock);
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++m_lockCount;
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}
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void ThreadLock::unlock() {
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if (m_lockCount == 0) {
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MMKVError("attempt to unlock unowned lock %p", &m_lock);
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return;
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}
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--m_lockCount;
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LeaveCriticalSection(&m_lock);
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}
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void ThreadLock::ThreadOnce(ThreadOnceToken_t *onceToken, void (*callback)()) {
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if (!onceToken || !callback) {
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assert(onceToken);
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assert(callback);
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return;
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}
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while (true) {
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auto expected = ThreadOnceUninitialized;
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atomic_compare_exchange_weak(onceToken, &expected, ThreadOnceInitializing);
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switch (expected) {
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case ThreadOnceInitialized:
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return;
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case ThreadOnceUninitialized:
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callback();
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onceToken->store(ThreadOnceInitialized);
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return;
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case ThreadOnceInitializing: {
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// another thread is initializing, let's wait for 1ms
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ThreadLock::Sleep(1);
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break;
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}
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default: {
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MMKVError("should never happen:%d", expected);
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assert(0);
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return;
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}
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}
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}
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}
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void ThreadLock::Sleep(int ms) {
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::Sleep(ms);
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}
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} // namespace mmkv
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#endif // MMKV_USING_PTHREAD
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