mirror of
https://github.com/ton-blockchain/ton
synced 2025-03-09 15:40:10 +00:00
82 lines
2 KiB
C++
82 lines
2 KiB
C++
/*
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This file is part of TON Blockchain Library.
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TON Blockchain Library is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 2 of the License, or
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(at your option) any later version.
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TON Blockchain Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with TON Blockchain Library. If not, see <http://www.gnu.org/licenses/>.
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Copyright 2017-2020 Telegram Systems LLP
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*/
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#include <atomic>
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#include "td/utils/common.h"
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#include "td/utils/port/thread.h"
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namespace td {
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template <class T>
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class AtomicRead {
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public:
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void read(T &dest) const {
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while (true) {
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static_assert(std::is_trivially_copyable<T>::value, "T must be trivially copyable");
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auto version_before = version.load();
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memcpy(&dest, &value, sizeof(dest));
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auto version_after = version.load();
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if (version_before == version_after && version_before % 2 == 0) {
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break;
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}
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td::this_thread::yield();
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}
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}
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friend struct Write;
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struct Write {
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explicit Write(AtomicRead *read) {
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read->do_lock();
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ptr.reset(read);
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}
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struct Destructor {
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void operator()(AtomicRead *read) const {
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read->do_unlock();
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}
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};
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T &operator*() {
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return value();
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}
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T *operator->() {
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return &value();
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}
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T &value() {
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CHECK(ptr);
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return ptr->value;
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}
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private:
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std::unique_ptr<AtomicRead, Destructor> ptr;
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};
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Write lock() {
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return Write(this);
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}
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private:
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std::atomic<td::uint64> version{0};
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T value;
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void do_lock() {
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CHECK(++version % 2 == 1);
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}
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void do_unlock() {
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CHECK(++version % 2 == 0);
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}
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};
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}; // namespace td
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