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73 lines
1.6 KiB
C++
73 lines
1.6 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 2017-2019 Telegram Systems LLP
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*/
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#pragma once
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#include "td/utils/port/thread.h"
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#include <atomic>
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#include <memory>
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namespace td {
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class SpinLock {
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struct Unlock {
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void operator()(SpinLock *ptr) {
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ptr->unlock();
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}
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};
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class InfBackoff {
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int cnt = 0;
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public:
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bool next() {
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cnt++;
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if (cnt < 50) {
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//TODO pause
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return true;
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} else {
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td::this_thread::yield();
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return true;
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}
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}
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};
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public:
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using Lock = std::unique_ptr<SpinLock, Unlock>;
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Lock lock() {
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InfBackoff backoff;
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while (!try_lock()) {
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backoff.next();
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}
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return Lock(this);
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}
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bool try_lock() {
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return !flag_.test_and_set(std::memory_order_acquire);
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}
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private:
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std::atomic_flag flag_ = ATOMIC_FLAG_INIT;
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void unlock() {
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flag_.clear(std::memory_order_release);
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}
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};
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} // namespace td
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