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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <chrono>
#include <ctime>
#include <exception>
#include <thread>
#include <type_traits>
namespace mongo {
namespace stdx {
/**
* We're wrapping std::thread here, rather than aliasing it, because we'd like
* a std::thread that's identical in all ways to the original, but terminates
* if a new thread cannot be allocated. We'd like this behavior because we
* rarely if ever try/catch thread creation, and don't have a strategy for
* retrying. Therefore, all throwing does is remove context as to which part
* of the system failed thread creation (as the exception itself is caught at
* the top of the stack).
*
* We're putting this in stdx, rather than having it as some kind of
* mongo::Thread, because the signature and use of the type is otherwise
* completely identical. Rather than migrate all callers, it was deemed
* simpler to make the in place adjustment and retain it in stdx.
*
* We implement this with private inheritance to minimize the overhead of our
* wrapping and to simplify the implementation.
*/
class thread : private ::std::thread { // NOLINT
public:
using ::std::thread::native_handle_type; // NOLINT
using ::std::thread::id; // NOLINT
thread() noexcept : ::std::thread::thread() {} // NOLINT
thread(const thread&) = delete;
thread(thread&& other) noexcept
: ::std::thread::thread(static_cast<::std::thread&&>(std::move(other))) {} // NOLINT
/**
* As of C++14, the Function overload for std::thread requires that this constructor only
* participate in overload resolution if std::decay_t<Function> is not the same type as thread.
* That prevents this overload from intercepting calls that might generate implicit conversions
* before binding to other constructors (specifically move/copy constructors).
*/
template <
class Function,
class... Args,
typename std::enable_if<!std::is_same<thread, typename std::decay<Function>::type>::value,
int>::type = 0>
explicit thread(Function&& f, Args&&... args) try:
::std::thread::thread(std::forward<Function>(f), std::forward<Args>(args)...) {} // NOLINT
catch (...) {
std::terminate();
}
thread& operator=(const thread&) = delete;
thread& operator=(thread&& other) noexcept {
return static_cast<thread&>(
::std::thread::operator=(static_cast<::std::thread&&>(std::move(other)))); // NOLINT
};
using ::std::thread::joinable; // NOLINT
using ::std::thread::get_id; // NOLINT
using ::std::thread::native_handle; // NOLINT
using ::std::thread::hardware_concurrency; // NOLINT
using ::std::thread::join; // NOLINT
using ::std::thread::detach; // NOLINT
void swap(thread& other) noexcept {
::std::thread::swap(static_cast<::std::thread&>(other)); // NOLINT
}
};
inline void swap(thread& lhs, thread& rhs) noexcept {
lhs.swap(rhs);
}
namespace this_thread {
using std::this_thread::get_id; // NOLINT
using std::this_thread::yield; // NOLINT
#ifdef _WIN32
using std::this_thread::sleep_for; // NOLINT
using std::this_thread::sleep_until; // NOLINT
#else
template <class Rep, class Period>
inline void sleep_for(const std::chrono::duration<Rep, Period>& sleep_duration) { // NOLINT
if (sleep_duration <= sleep_duration.zero())
return;
const auto seconds =
std::chrono::duration_cast<std::chrono::seconds>(sleep_duration); // NOLINT
const auto nanoseconds =
std::chrono::duration_cast<std::chrono::nanoseconds>(sleep_duration - seconds); // NOLINT
struct timespec sleepVal = {static_cast<std::time_t>(seconds.count()),
static_cast<long>(nanoseconds.count())};
struct timespec remainVal;
while (nanosleep(&sleepVal, &remainVal) == -1 && errno == EINTR) {
sleepVal = remainVal;
}
}
template <class Clock, class Duration>
void sleep_until(const std::chrono::time_point<Clock, Duration>& sleep_time) { // NOLINT
const auto now = Clock::now();
sleep_for(sleep_time - now);
}
#endif
} // namespace this_thread
} // namespace stdx
} // namespace mongo
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