Files
scylladb/clocks-impl.hh
Avi Kivity fcb8d040e8 treewide: use Software Package Data Exchange (SPDX) license identifiers
Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.

Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.

The changes we applied mechanically with a script, except to
licenses/README.md.

Closes #9937
2022-01-18 12:15:18 +01:00

37 lines
986 B
C++

/*
* Copyright (C) 2017-present ScyllaDB
*/
/*
* SPDX-License-Identifier: AGPL-3.0-or-later
*/
#pragma once
#include <algorithm>
#include <atomic>
#include <chrono>
#include <cstdint>
extern std::atomic<int64_t> clocks_offset;
template<typename Duration>
static inline void forward_jump_clocks(Duration delta)
{
auto d = std::chrono::duration_cast<std::chrono::seconds>(delta).count();
clocks_offset.fetch_add(d, std::memory_order_relaxed);
}
static inline std::chrono::seconds get_clocks_offset()
{
auto off = clocks_offset.load(std::memory_order_relaxed);
return std::chrono::seconds(off);
}
// Returns a time point which is earlier from t by d, or minimum time point if it cannot be represented.
template<typename Clock, typename Duration, typename Rep, typename Period>
inline
auto saturating_subtract(std::chrono::time_point<Clock, Duration> t, std::chrono::duration<Rep, Period> d) -> decltype(t) {
return std::max(t, decltype(t)::min() + d) - d;
}