1 //===--- Linux absolute timeout ---------------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef LLVM_LIBC_SRC___SUPPORT_TIME_LINUX_ABS_TIMEOUT_H 10 #define LLVM_LIBC_SRC___SUPPORT_TIME_LINUX_ABS_TIMEOUT_H 11 12 #include "hdr/time_macros.h" 13 #include "hdr/types/struct_timespec.h" 14 #include "src/__support/CPP/expected.h" 15 #include "src/__support/time/units.h" 16 17 namespace LIBC_NAMESPACE { 18 namespace internal { 19 // We use AbsTimeout to remind ourselves that the timeout is an absolute time. 20 // This is a simple wrapper around the timespec struct that also keeps track of 21 // whether the time is in realtime or monotonic time. 22 class AbsTimeout { 23 timespec timeout; 24 bool realtime_flag; AbsTimeout(timespec ts,bool realtime)25 LIBC_INLINE constexpr explicit AbsTimeout(timespec ts, bool realtime) 26 : timeout(ts), realtime_flag(realtime) {} 27 28 public: 29 enum class Error { Invalid, BeforeEpoch }; get_timespec()30 LIBC_INLINE const timespec &get_timespec() const { return timeout; } is_realtime()31 LIBC_INLINE bool is_realtime() const { return realtime_flag; } 32 LIBC_INLINE static constexpr cpp::expected<AbsTimeout, Error> from_timespec(timespec ts,bool realtime)33 from_timespec(timespec ts, bool realtime) { 34 using namespace time_units; 35 if (ts.tv_nsec < 0 || ts.tv_nsec >= 1_s_ns) 36 return cpp::unexpected(Error::Invalid); 37 38 // POSIX allows tv_sec to be negative. We interpret this as an expired 39 // timeout. 40 if (ts.tv_sec < 0) 41 return cpp::unexpected(Error::BeforeEpoch); 42 43 return AbsTimeout{ts, realtime}; 44 } 45 }; 46 } // namespace internal 47 } // namespace LIBC_NAMESPACE 48 49 #endif // LLVM_LIBC_SRC___SUPPORT_TIME_LINUX_ABS_TIMEOUT_H 50