absl/synchronization/internal/kernel_timeout_test.cc - third_party/github/abseil/abseil-cpp - Git at Google

 // Copyright 2023 The Abseil Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     https://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 #include "absl/synchronization/internal/kernel_timeout.h"

 #include <ctime>
 #include <chrono>  // NOLINT(build/c++11)
 #include <limits>

 #include "absl/base/config.h"
 #include "absl/random/random.h"
 #include "absl/time/clock.h"
 #include "absl/time/time.h"
 #include "gtest/gtest.h"

 // Test go/btm support by randomizing the value of clock_gettime() for
 // CLOCK_MONOTONIC. This works by overriding a weak symbol in glibc.
 // We should be resistant to this randomization when !SupportsSteadyClock().
 #if defined(__GOOGLE_GRTE_VERSION__) &&      \
     !defined(ABSL_HAVE_ADDRESS_SANITIZER) && \
     !defined(ABSL_HAVE_MEMORY_SANITIZER) &&  \
     !defined(ABSL_HAVE_THREAD_SANITIZER)
 extern "C" int __clock_gettime(clockid_t c, struct timespec* ts);

 extern "C" int clock_gettime(clockid_t c, struct timespec* ts) {
   if (c == CLOCK_MONOTONIC &&
       !absl::synchronization_internal::KernelTimeout::SupportsSteadyClock()) {
     thread_local absl::BitGen gen;  // NOLINT
     ts->tv_sec = absl::Uniform(gen, 0, 1'000'000'000);
     ts->tv_nsec = absl::Uniform(gen, 0, 1'000'000'000);
     return 0;
   }
   return __clock_gettime(c, ts);
 }
 #endif

 namespace {

 #if defined(ABSL_HAVE_ADDRESS_SANITIZER) ||                        \
     defined(ABSL_HAVE_MEMORY_SANITIZER) ||                         \
     defined(ABSL_HAVE_THREAD_SANITIZER) || defined(__ANDROID__) || \
     defined(__APPLE__) || defined(_WIN32) || defined(_WIN64)
 constexpr absl::Duration kTimingBound = absl::Milliseconds(5);
 #else
 constexpr absl::Duration kTimingBound = absl::Microseconds(250);
 #endif

 using absl::synchronization_internal::KernelTimeout;

 TEST(KernelTimeout, FiniteTimes) {
   constexpr absl::Duration kDurationsToTest[] = {
     absl::ZeroDuration(),
     absl::Nanoseconds(1),
     absl::Microseconds(1),
     absl::Milliseconds(1),
     absl::Seconds(1),
     absl::Minutes(1),
     absl::Hours(1),
     absl::Hours(1000),
     -absl::Nanoseconds(1),
     -absl::Microseconds(1),
     -absl::Milliseconds(1),
     -absl::Seconds(1),
     -absl::Minutes(1),
     -absl::Hours(1),
     -absl::Hours(1000),
   };

   for (auto duration : kDurationsToTest) {
     const absl::Time now = absl::Now();
     const absl::Time when = now + duration;
     SCOPED_TRACE(duration);
     KernelTimeout t(when);
     EXPECT_TRUE(t.has_timeout());
     EXPECT_TRUE(t.is_absolute_timeout());
     EXPECT_FALSE(t.is_relative_timeout());
     EXPECT_EQ(absl::TimeFromTimespec(t.MakeAbsTimespec()), when);
 #ifndef _WIN32
     EXPECT_LE(
         absl::AbsDuration(absl::Now() + duration -
                           absl::TimeFromTimespec(
                               t.MakeClockAbsoluteTimespec(CLOCK_REALTIME))),
         absl::Milliseconds(10));
 #endif
     EXPECT_LE(
         absl::AbsDuration(absl::DurationFromTimespec(t.MakeRelativeTimespec()) -
                           std::max(duration, absl::ZeroDuration())),
         kTimingBound);
     EXPECT_EQ(absl::FromUnixNanos(t.MakeAbsNanos()), when);
     EXPECT_LE(absl::AbsDuration(absl::Milliseconds(t.InMillisecondsFromNow()) -
                                 std::max(duration, absl::ZeroDuration())),
               absl::Milliseconds(5));
     EXPECT_LE(absl::AbsDuration(absl::FromChrono(t.ToChronoTimePoint()) - when),
               absl::Microseconds(1));
     EXPECT_LE(absl::AbsDuration(absl::FromChrono(t.ToChronoDuration()) -
                                 std::max(duration, absl::ZeroDuration())),
               kTimingBound);
   }
 }

 TEST(KernelTimeout, InfiniteFuture) {
   KernelTimeout t(absl::InfiniteFuture());
   EXPECT_FALSE(t.has_timeout());
   // Callers are expected to check has_timeout() instead of using the methods
   // below, but we do try to do something reasonable if they don't. We may not
   // be able to round-trip back to absl::InfiniteDuration() or
   // absl::InfiniteFuture(), but we should return a very large value.
   EXPECT_GT(absl::TimeFromTimespec(t.MakeAbsTimespec()),
             absl::Now() + absl::Hours(100000));
 #ifndef _WIN32
   EXPECT_GT(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
             absl::Now() + absl::Hours(100000));
 #endif
   EXPECT_GT(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
             absl::Hours(100000));
   EXPECT_GT(absl::FromUnixNanos(t.MakeAbsNanos()),
             absl::Now() + absl::Hours(100000));
   EXPECT_EQ(t.InMillisecondsFromNow(),
             std::numeric_limits<KernelTimeout::DWord>::max());
   EXPECT_EQ(t.ToChronoTimePoint(),
             std::chrono::time_point<std::chrono::system_clock>::max());
   EXPECT_GE(t.ToChronoDuration(), std::chrono::nanoseconds::max());
 }

 TEST(KernelTimeout, DefaultConstructor) {
   // The default constructor is equivalent to absl::InfiniteFuture().
   KernelTimeout t;
   EXPECT_FALSE(t.has_timeout());
   // Callers are expected to check has_timeout() instead of using the methods
   // below, but we do try to do something reasonable if they don't. We may not
   // be able to round-trip back to absl::InfiniteDuration() or
   // absl::InfiniteFuture(), but we should return a very large value.
   EXPECT_GT(absl::TimeFromTimespec(t.MakeAbsTimespec()),
             absl::Now() + absl::Hours(100000));
 #ifndef _WIN32
   EXPECT_GT(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
             absl::Now() + absl::Hours(100000));
 #endif
   EXPECT_GT(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
             absl::Hours(100000));
   EXPECT_GT(absl::FromUnixNanos(t.MakeAbsNanos()),
             absl::Now() + absl::Hours(100000));
   EXPECT_EQ(t.InMillisecondsFromNow(),
             std::numeric_limits<KernelTimeout::DWord>::max());
   EXPECT_EQ(t.ToChronoTimePoint(),
             std::chrono::time_point<std::chrono::system_clock>::max());
   EXPECT_GE(t.ToChronoDuration(), std::chrono::nanoseconds::max());
 }

 TEST(KernelTimeout, TimeMaxNanos) {
   // Time >= kMaxNanos should behave as no timeout.
   KernelTimeout t(absl::FromUnixNanos(std::numeric_limits<int64_t>::max()));
   EXPECT_FALSE(t.has_timeout());
   // Callers are expected to check has_timeout() instead of using the methods
   // below, but we do try to do something reasonable if they don't. We may not
   // be able to round-trip back to absl::InfiniteDuration() or
   // absl::InfiniteFuture(), but we should return a very large value.
   EXPECT_GT(absl::TimeFromTimespec(t.MakeAbsTimespec()),
             absl::Now() + absl::Hours(100000));
 #ifndef _WIN32
   EXPECT_GT(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
             absl::Now() + absl::Hours(100000));
 #endif
   EXPECT_GT(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
             absl::Hours(100000));
   EXPECT_GT(absl::FromUnixNanos(t.MakeAbsNanos()),
             absl::Now() + absl::Hours(100000));
   EXPECT_EQ(t.InMillisecondsFromNow(),
             std::numeric_limits<KernelTimeout::DWord>::max());
   EXPECT_EQ(t.ToChronoTimePoint(),
             std::chrono::time_point<std::chrono::system_clock>::max());
   EXPECT_GE(t.ToChronoDuration(), std::chrono::nanoseconds::max());
 }

 TEST(KernelTimeout, Never) {
   // KernelTimeout::Never() is equivalent to absl::InfiniteFuture().
   KernelTimeout t = KernelTimeout::Never();
   EXPECT_FALSE(t.has_timeout());
   // Callers are expected to check has_timeout() instead of using the methods
   // below, but we do try to do something reasonable if they don't. We may not
   // be able to round-trip back to absl::InfiniteDuration() or
   // absl::InfiniteFuture(), but we should return a very large value.
   EXPECT_GT(absl::TimeFromTimespec(t.MakeAbsTimespec()),
             absl::Now() + absl::Hours(100000));
 #ifndef _WIN32
   EXPECT_GT(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
             absl::Now() + absl::Hours(100000));
 #endif
   EXPECT_GT(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
             absl::Hours(100000));
   EXPECT_GT(absl::FromUnixNanos(t.MakeAbsNanos()),
             absl::Now() + absl::Hours(100000));
   EXPECT_EQ(t.InMillisecondsFromNow(),
             std::numeric_limits<KernelTimeout::DWord>::max());
   EXPECT_EQ(t.ToChronoTimePoint(),
             std::chrono::time_point<std::chrono::system_clock>::max());
   EXPECT_GE(t.ToChronoDuration(), std::chrono::nanoseconds::max());
 }

 TEST(KernelTimeout, InfinitePast) {
   KernelTimeout t(absl::InfinitePast());
   EXPECT_TRUE(t.has_timeout());
   EXPECT_TRUE(t.is_absolute_timeout());
   EXPECT_FALSE(t.is_relative_timeout());
   EXPECT_LE(absl::TimeFromTimespec(t.MakeAbsTimespec()),
             absl::FromUnixNanos(1));
 #ifndef _WIN32
   EXPECT_LE(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
             absl::FromUnixSeconds(1));
 #endif
   EXPECT_EQ(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
             absl::ZeroDuration());
   EXPECT_LE(absl::FromUnixNanos(t.MakeAbsNanos()), absl::FromUnixNanos(1));
   EXPECT_EQ(t.InMillisecondsFromNow(), KernelTimeout::DWord{0});
   EXPECT_LT(t.ToChronoTimePoint(), std::chrono::system_clock::from_time_t(0) +
                                        std::chrono::seconds(1));
   EXPECT_EQ(t.ToChronoDuration(), std::chrono::nanoseconds(0));
 }

 TEST(KernelTimeout, FiniteDurations) {
   constexpr absl::Duration kDurationsToTest[] = {
     absl::ZeroDuration(),
     absl::Nanoseconds(1),
     absl::Microseconds(1),
     absl::Milliseconds(1),
     absl::Seconds(1),
     absl::Minutes(1),
     absl::Hours(1),
     absl::Hours(1000),
   };

   for (auto duration : kDurationsToTest) {
     SCOPED_TRACE(duration);
     KernelTimeout t(duration);
     EXPECT_TRUE(t.has_timeout());
     EXPECT_FALSE(t.is_absolute_timeout());
     EXPECT_TRUE(t.is_relative_timeout());
     EXPECT_LE(absl::AbsDuration(absl::Now() + duration -
                                 absl::TimeFromTimespec(t.MakeAbsTimespec())),
               absl::Milliseconds(5));
 #ifndef _WIN32
     EXPECT_LE(
         absl::AbsDuration(absl::Now() + duration -
                           absl::TimeFromTimespec(
                               t.MakeClockAbsoluteTimespec(CLOCK_REALTIME))),
         absl::Milliseconds(5));
 #endif
     EXPECT_LE(
         absl::AbsDuration(absl::DurationFromTimespec(t.MakeRelativeTimespec()) -
                           duration),
         kTimingBound);
     EXPECT_LE(absl::AbsDuration(absl::Now() + duration -
                                 absl::FromUnixNanos(t.MakeAbsNanos())),
               absl::Milliseconds(5));
     EXPECT_LE(absl::Milliseconds(t.InMillisecondsFromNow()) - duration,
               absl::Milliseconds(5));
     EXPECT_LE(absl::AbsDuration(absl::Now() + duration -
                                 absl::FromChrono(t.ToChronoTimePoint())),
               kTimingBound);
     EXPECT_LE(
         absl::AbsDuration(absl::FromChrono(t.ToChronoDuration()) - duration),
         kTimingBound);
   }
 }

 TEST(KernelTimeout, NegativeDurations) {
   constexpr absl::Duration kDurationsToTest[] = {
     -absl::ZeroDuration(),
     -absl::Nanoseconds(1),
     -absl::Microseconds(1),
     -absl::Milliseconds(1),
     -absl::Seconds(1),
     -absl::Minutes(1),
     -absl::Hours(1),
     -absl::Hours(1000),
     -absl::InfiniteDuration(),
   };

   for (auto duration : kDurationsToTest) {
     // Negative durations should all be converted to zero durations or "now".
     SCOPED_TRACE(duration);
     KernelTimeout t(duration);
     EXPECT_TRUE(t.has_timeout());
     EXPECT_FALSE(t.is_absolute_timeout());
     EXPECT_TRUE(t.is_relative_timeout());
     EXPECT_LE(absl::AbsDuration(absl::Now() -
                                 absl::TimeFromTimespec(t.MakeAbsTimespec())),
               absl::Milliseconds(5));
 #ifndef _WIN32
     EXPECT_LE(absl::AbsDuration(absl::Now() - absl::TimeFromTimespec(
                                                   t.MakeClockAbsoluteTimespec(
                                                       CLOCK_REALTIME))),
               absl::Milliseconds(5));
 #endif
     EXPECT_EQ(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
               absl::ZeroDuration());
     EXPECT_LE(
         absl::AbsDuration(absl::Now() - absl::FromUnixNanos(t.MakeAbsNanos())),
         absl::Milliseconds(5));
     EXPECT_EQ(t.InMillisecondsFromNow(), KernelTimeout::DWord{0});
     EXPECT_LE(absl::AbsDuration(absl::Now() -
                                 absl::FromChrono(t.ToChronoTimePoint())),
               absl::Milliseconds(5));
     EXPECT_EQ(t.ToChronoDuration(), std::chrono::nanoseconds(0));
   }
 }

 TEST(KernelTimeout, InfiniteDuration) {
   KernelTimeout t(absl::InfiniteDuration());
   EXPECT_FALSE(t.has_timeout());
   // Callers are expected to check has_timeout() instead of using the methods
   // below, but we do try to do something reasonable if they don't. We may not
   // be able to round-trip back to absl::InfiniteDuration() or
   // absl::InfiniteFuture(), but we should return a very large value.
   EXPECT_GT(absl::TimeFromTimespec(t.MakeAbsTimespec()),
             absl::Now() + absl::Hours(100000));
 #ifndef _WIN32
   EXPECT_GT(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
             absl::Now() + absl::Hours(100000));
 #endif
   EXPECT_GT(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
             absl::Hours(100000));
   EXPECT_GT(absl::FromUnixNanos(t.MakeAbsNanos()),
             absl::Now() + absl::Hours(100000));
   EXPECT_EQ(t.InMillisecondsFromNow(),
             std::numeric_limits<KernelTimeout::DWord>::max());
   EXPECT_EQ(t.ToChronoTimePoint(),
             std::chrono::time_point<std::chrono::system_clock>::max());
   EXPECT_GE(t.ToChronoDuration(), std::chrono::nanoseconds::max());
 }

 TEST(KernelTimeout, DurationMaxNanos) {
   // Duration >= kMaxNanos should behave as no timeout.
   KernelTimeout t(absl::Nanoseconds(std::numeric_limits<int64_t>::max()));
   EXPECT_FALSE(t.has_timeout());
   // Callers are expected to check has_timeout() instead of using the methods
   // below, but we do try to do something reasonable if they don't. We may not
   // be able to round-trip back to absl::InfiniteDuration() or
   // absl::InfiniteFuture(), but we should return a very large value.
   EXPECT_GT(absl::TimeFromTimespec(t.MakeAbsTimespec()),
             absl::Now() + absl::Hours(100000));
 #ifndef _WIN32
   EXPECT_GT(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
             absl::Now() + absl::Hours(100000));
 #endif
   EXPECT_GT(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
             absl::Hours(100000));
   EXPECT_GT(absl::FromUnixNanos(t.MakeAbsNanos()),
             absl::Now() + absl::Hours(100000));
   EXPECT_EQ(t.InMillisecondsFromNow(),
             std::numeric_limits<KernelTimeout::DWord>::max());
   EXPECT_EQ(t.ToChronoTimePoint(),
             std::chrono::time_point<std::chrono::system_clock>::max());
   EXPECT_GE(t.ToChronoDuration(), std::chrono::nanoseconds::max());
 }

 TEST(KernelTimeout, OverflowNanos) {
   // Test what happens when KernelTimeout is constructed with an absl::Duration
   // that would overflow now_nanos + duration.
   int64_t now_nanos = absl::ToUnixNanos(absl::Now());
   int64_t limit = std::numeric_limits<int64_t>::max() - now_nanos;
   absl::Duration duration = absl::Nanoseconds(limit) + absl::Seconds(1);
   KernelTimeout t(duration);
   // Timeouts should still be far in the future.
   EXPECT_GT(absl::TimeFromTimespec(t.MakeAbsTimespec()),
             absl::Now() + absl::Hours(100000));
 #ifndef _WIN32
   EXPECT_GT(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
             absl::Now() + absl::Hours(100000));
 #endif
   EXPECT_GT(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
             absl::Hours(100000));
   EXPECT_GT(absl::FromUnixNanos(t.MakeAbsNanos()),
             absl::Now() + absl::Hours(100000));
   EXPECT_LE(absl::Milliseconds(t.InMillisecondsFromNow()) - duration,
             absl::Milliseconds(5));
   EXPECT_GT(t.ToChronoTimePoint(),
             std::chrono::system_clock::now() + std::chrono::hours(100000));
   EXPECT_GT(t.ToChronoDuration(), std::chrono::hours(100000));
 }

 }  // namespace
	// Copyright 2023 The Abseil Authors
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// https://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	#include "absl/synchronization/internal/kernel_timeout.h"

	#include <ctime>
	#include <chrono> // NOLINT(build/c++11)
	#include <limits>

	#include "absl/base/config.h"
	#include "absl/random/random.h"
	#include "absl/time/clock.h"
	#include "absl/time/time.h"
	#include "gtest/gtest.h"

	// Test go/btm support by randomizing the value of clock_gettime() for
	// CLOCK_MONOTONIC. This works by overriding a weak symbol in glibc.
	// We should be resistant to this randomization when !SupportsSteadyClock().
	#if defined(__GOOGLE_GRTE_VERSION__) && \
	!defined(ABSL_HAVE_ADDRESS_SANITIZER) && \
	!defined(ABSL_HAVE_MEMORY_SANITIZER) && \
	!defined(ABSL_HAVE_THREAD_SANITIZER)
	extern "C" int __clock_gettime(clockid_t c, struct timespec* ts);

	extern "C" int clock_gettime(clockid_t c, struct timespec* ts) {
	if (c == CLOCK_MONOTONIC &&
	!absl::synchronization_internal::KernelTimeout::SupportsSteadyClock()) {
	thread_local absl::BitGen gen; // NOLINT
	ts->tv_sec = absl::Uniform(gen, 0, 1'000'000'000);
	ts->tv_nsec = absl::Uniform(gen, 0, 1'000'000'000);
	return 0;
	}
	return __clock_gettime(c, ts);
	}
	#endif

	namespace {

	#if defined(ABSL_HAVE_ADDRESS_SANITIZER) \|\| \
	defined(ABSL_HAVE_MEMORY_SANITIZER) \|\| \
	defined(ABSL_HAVE_THREAD_SANITIZER) \|\| defined(__ANDROID__) \|\| \
	defined(__APPLE__) \|\| defined(_WIN32) \|\| defined(_WIN64)
	constexpr absl::Duration kTimingBound = absl::Milliseconds(5);
	#else
	constexpr absl::Duration kTimingBound = absl::Microseconds(250);
	#endif

	using absl::synchronization_internal::KernelTimeout;

	TEST(KernelTimeout, FiniteTimes) {
	constexpr absl::Duration kDurationsToTest[] = {
	absl::ZeroDuration(),
	absl::Nanoseconds(1),
	absl::Microseconds(1),
	absl::Milliseconds(1),
	absl::Seconds(1),
	absl::Minutes(1),
	absl::Hours(1),
	absl::Hours(1000),
	-absl::Nanoseconds(1),
	-absl::Microseconds(1),
	-absl::Milliseconds(1),
	-absl::Seconds(1),
	-absl::Minutes(1),
	-absl::Hours(1),
	-absl::Hours(1000),
	};

	for (auto duration : kDurationsToTest) {
	const absl::Time now = absl::Now();
	const absl::Time when = now + duration;
	SCOPED_TRACE(duration);
	KernelTimeout t(when);
	EXPECT_TRUE(t.has_timeout());
	EXPECT_TRUE(t.is_absolute_timeout());
	EXPECT_FALSE(t.is_relative_timeout());
	EXPECT_EQ(absl::TimeFromTimespec(t.MakeAbsTimespec()), when);
	#ifndef _WIN32
	EXPECT_LE(
	absl::AbsDuration(absl::Now() + duration -
	absl::TimeFromTimespec(
	t.MakeClockAbsoluteTimespec(CLOCK_REALTIME))),
	absl::Milliseconds(10));
	#endif
	EXPECT_LE(
	absl::AbsDuration(absl::DurationFromTimespec(t.MakeRelativeTimespec()) -
	std::max(duration, absl::ZeroDuration())),
	kTimingBound);
	EXPECT_EQ(absl::FromUnixNanos(t.MakeAbsNanos()), when);
	EXPECT_LE(absl::AbsDuration(absl::Milliseconds(t.InMillisecondsFromNow()) -
	std::max(duration, absl::ZeroDuration())),
	absl::Milliseconds(5));
	EXPECT_LE(absl::AbsDuration(absl::FromChrono(t.ToChronoTimePoint()) - when),
	absl::Microseconds(1));
	EXPECT_LE(absl::AbsDuration(absl::FromChrono(t.ToChronoDuration()) -
	std::max(duration, absl::ZeroDuration())),
	kTimingBound);
	}
	}

	TEST(KernelTimeout, InfiniteFuture) {
	KernelTimeout t(absl::InfiniteFuture());
	EXPECT_FALSE(t.has_timeout());
	// Callers are expected to check has_timeout() instead of using the methods
	// below, but we do try to do something reasonable if they don't. We may not
	// be able to round-trip back to absl::InfiniteDuration() or
	// absl::InfiniteFuture(), but we should return a very large value.
	EXPECT_GT(absl::TimeFromTimespec(t.MakeAbsTimespec()),
	absl::Now() + absl::Hours(100000));
	#ifndef _WIN32
	EXPECT_GT(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
	absl::Now() + absl::Hours(100000));
	#endif
	EXPECT_GT(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
	absl::Hours(100000));
	EXPECT_GT(absl::FromUnixNanos(t.MakeAbsNanos()),
	absl::Now() + absl::Hours(100000));
	EXPECT_EQ(t.InMillisecondsFromNow(),
	std::numeric_limits<KernelTimeout::DWord>::max());
	EXPECT_EQ(t.ToChronoTimePoint(),
	std::chrono::time_point<std::chrono::system_clock>::max());
	EXPECT_GE(t.ToChronoDuration(), std::chrono::nanoseconds::max());
	}

	TEST(KernelTimeout, DefaultConstructor) {
	// The default constructor is equivalent to absl::InfiniteFuture().
	KernelTimeout t;
	EXPECT_FALSE(t.has_timeout());
	// Callers are expected to check has_timeout() instead of using the methods
	// below, but we do try to do something reasonable if they don't. We may not
	// be able to round-trip back to absl::InfiniteDuration() or
	// absl::InfiniteFuture(), but we should return a very large value.
	EXPECT_GT(absl::TimeFromTimespec(t.MakeAbsTimespec()),
	absl::Now() + absl::Hours(100000));
	#ifndef _WIN32
	EXPECT_GT(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
	absl::Now() + absl::Hours(100000));
	#endif
	EXPECT_GT(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
	absl::Hours(100000));
	EXPECT_GT(absl::FromUnixNanos(t.MakeAbsNanos()),
	absl::Now() + absl::Hours(100000));
	EXPECT_EQ(t.InMillisecondsFromNow(),
	std::numeric_limits<KernelTimeout::DWord>::max());
	EXPECT_EQ(t.ToChronoTimePoint(),
	std::chrono::time_point<std::chrono::system_clock>::max());
	EXPECT_GE(t.ToChronoDuration(), std::chrono::nanoseconds::max());
	}

	TEST(KernelTimeout, TimeMaxNanos) {
	// Time >= kMaxNanos should behave as no timeout.
	KernelTimeout t(absl::FromUnixNanos(std::numeric_limits<int64_t>::max()));
	EXPECT_FALSE(t.has_timeout());
	// Callers are expected to check has_timeout() instead of using the methods
	// below, but we do try to do something reasonable if they don't. We may not
	// be able to round-trip back to absl::InfiniteDuration() or
	// absl::InfiniteFuture(), but we should return a very large value.
	EXPECT_GT(absl::TimeFromTimespec(t.MakeAbsTimespec()),
	absl::Now() + absl::Hours(100000));
	#ifndef _WIN32
	EXPECT_GT(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
	absl::Now() + absl::Hours(100000));
	#endif
	EXPECT_GT(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
	absl::Hours(100000));
	EXPECT_GT(absl::FromUnixNanos(t.MakeAbsNanos()),
	absl::Now() + absl::Hours(100000));
	EXPECT_EQ(t.InMillisecondsFromNow(),
	std::numeric_limits<KernelTimeout::DWord>::max());
	EXPECT_EQ(t.ToChronoTimePoint(),
	std::chrono::time_point<std::chrono::system_clock>::max());
	EXPECT_GE(t.ToChronoDuration(), std::chrono::nanoseconds::max());
	}

	TEST(KernelTimeout, Never) {
	// KernelTimeout::Never() is equivalent to absl::InfiniteFuture().
	KernelTimeout t = KernelTimeout::Never();
	EXPECT_FALSE(t.has_timeout());
	// Callers are expected to check has_timeout() instead of using the methods
	// below, but we do try to do something reasonable if they don't. We may not
	// be able to round-trip back to absl::InfiniteDuration() or
	// absl::InfiniteFuture(), but we should return a very large value.
	EXPECT_GT(absl::TimeFromTimespec(t.MakeAbsTimespec()),
	absl::Now() + absl::Hours(100000));
	#ifndef _WIN32
	EXPECT_GT(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
	absl::Now() + absl::Hours(100000));
	#endif
	EXPECT_GT(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
	absl::Hours(100000));
	EXPECT_GT(absl::FromUnixNanos(t.MakeAbsNanos()),
	absl::Now() + absl::Hours(100000));
	EXPECT_EQ(t.InMillisecondsFromNow(),
	std::numeric_limits<KernelTimeout::DWord>::max());
	EXPECT_EQ(t.ToChronoTimePoint(),
	std::chrono::time_point<std::chrono::system_clock>::max());
	EXPECT_GE(t.ToChronoDuration(), std::chrono::nanoseconds::max());
	}

	TEST(KernelTimeout, InfinitePast) {
	KernelTimeout t(absl::InfinitePast());
	EXPECT_TRUE(t.has_timeout());
	EXPECT_TRUE(t.is_absolute_timeout());
	EXPECT_FALSE(t.is_relative_timeout());
	EXPECT_LE(absl::TimeFromTimespec(t.MakeAbsTimespec()),
	absl::FromUnixNanos(1));
	#ifndef _WIN32
	EXPECT_LE(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
	absl::FromUnixSeconds(1));
	#endif
	EXPECT_EQ(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
	absl::ZeroDuration());
	EXPECT_LE(absl::FromUnixNanos(t.MakeAbsNanos()), absl::FromUnixNanos(1));
	EXPECT_EQ(t.InMillisecondsFromNow(), KernelTimeout::DWord{0});
	EXPECT_LT(t.ToChronoTimePoint(), std::chrono::system_clock::from_time_t(0) +
	std::chrono::seconds(1));
	EXPECT_EQ(t.ToChronoDuration(), std::chrono::nanoseconds(0));
	}

	TEST(KernelTimeout, FiniteDurations) {
	constexpr absl::Duration kDurationsToTest[] = {
	absl::ZeroDuration(),
	absl::Nanoseconds(1),
	absl::Microseconds(1),
	absl::Milliseconds(1),
	absl::Seconds(1),
	absl::Minutes(1),
	absl::Hours(1),
	absl::Hours(1000),
	};

	for (auto duration : kDurationsToTest) {
	SCOPED_TRACE(duration);
	KernelTimeout t(duration);
	EXPECT_TRUE(t.has_timeout());
	EXPECT_FALSE(t.is_absolute_timeout());
	EXPECT_TRUE(t.is_relative_timeout());
	EXPECT_LE(absl::AbsDuration(absl::Now() + duration -
	absl::TimeFromTimespec(t.MakeAbsTimespec())),
	absl::Milliseconds(5));
	#ifndef _WIN32
	EXPECT_LE(
	absl::AbsDuration(absl::Now() + duration -
	absl::TimeFromTimespec(
	t.MakeClockAbsoluteTimespec(CLOCK_REALTIME))),
	absl::Milliseconds(5));
	#endif
	EXPECT_LE(
	absl::AbsDuration(absl::DurationFromTimespec(t.MakeRelativeTimespec()) -
	duration),
	kTimingBound);
	EXPECT_LE(absl::AbsDuration(absl::Now() + duration -
	absl::FromUnixNanos(t.MakeAbsNanos())),
	absl::Milliseconds(5));
	EXPECT_LE(absl::Milliseconds(t.InMillisecondsFromNow()) - duration,
	absl::Milliseconds(5));
	EXPECT_LE(absl::AbsDuration(absl::Now() + duration -
	absl::FromChrono(t.ToChronoTimePoint())),
	kTimingBound);
	EXPECT_LE(
	absl::AbsDuration(absl::FromChrono(t.ToChronoDuration()) - duration),
	kTimingBound);
	}
	}

	TEST(KernelTimeout, NegativeDurations) {
	constexpr absl::Duration kDurationsToTest[] = {
	-absl::ZeroDuration(),
	-absl::Nanoseconds(1),
	-absl::Microseconds(1),
	-absl::Milliseconds(1),
	-absl::Seconds(1),
	-absl::Minutes(1),
	-absl::Hours(1),
	-absl::Hours(1000),
	-absl::InfiniteDuration(),
	};

	for (auto duration : kDurationsToTest) {
	// Negative durations should all be converted to zero durations or "now".
	SCOPED_TRACE(duration);
	KernelTimeout t(duration);
	EXPECT_TRUE(t.has_timeout());
	EXPECT_FALSE(t.is_absolute_timeout());
	EXPECT_TRUE(t.is_relative_timeout());
	EXPECT_LE(absl::AbsDuration(absl::Now() -
	absl::TimeFromTimespec(t.MakeAbsTimespec())),
	absl::Milliseconds(5));
	#ifndef _WIN32
	EXPECT_LE(absl::AbsDuration(absl::Now() - absl::TimeFromTimespec(
	t.MakeClockAbsoluteTimespec(
	CLOCK_REALTIME))),
	absl::Milliseconds(5));
	#endif
	EXPECT_EQ(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
	absl::ZeroDuration());
	EXPECT_LE(
	absl::AbsDuration(absl::Now() - absl::FromUnixNanos(t.MakeAbsNanos())),
	absl::Milliseconds(5));
	EXPECT_EQ(t.InMillisecondsFromNow(), KernelTimeout::DWord{0});
	EXPECT_LE(absl::AbsDuration(absl::Now() -
	absl::FromChrono(t.ToChronoTimePoint())),
	absl::Milliseconds(5));
	EXPECT_EQ(t.ToChronoDuration(), std::chrono::nanoseconds(0));
	}
	}

	TEST(KernelTimeout, InfiniteDuration) {
	KernelTimeout t(absl::InfiniteDuration());
	EXPECT_FALSE(t.has_timeout());
	// Callers are expected to check has_timeout() instead of using the methods
	// below, but we do try to do something reasonable if they don't. We may not
	// be able to round-trip back to absl::InfiniteDuration() or
	// absl::InfiniteFuture(), but we should return a very large value.
	EXPECT_GT(absl::TimeFromTimespec(t.MakeAbsTimespec()),
	absl::Now() + absl::Hours(100000));
	#ifndef _WIN32
	EXPECT_GT(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
	absl::Now() + absl::Hours(100000));
	#endif
	EXPECT_GT(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
	absl::Hours(100000));
	EXPECT_GT(absl::FromUnixNanos(t.MakeAbsNanos()),
	absl::Now() + absl::Hours(100000));
	EXPECT_EQ(t.InMillisecondsFromNow(),
	std::numeric_limits<KernelTimeout::DWord>::max());
	EXPECT_EQ(t.ToChronoTimePoint(),
	std::chrono::time_point<std::chrono::system_clock>::max());
	EXPECT_GE(t.ToChronoDuration(), std::chrono::nanoseconds::max());
	}

	TEST(KernelTimeout, DurationMaxNanos) {
	// Duration >= kMaxNanos should behave as no timeout.
	KernelTimeout t(absl::Nanoseconds(std::numeric_limits<int64_t>::max()));
	EXPECT_FALSE(t.has_timeout());
	// Callers are expected to check has_timeout() instead of using the methods
	// below, but we do try to do something reasonable if they don't. We may not
	// be able to round-trip back to absl::InfiniteDuration() or
	// absl::InfiniteFuture(), but we should return a very large value.
	EXPECT_GT(absl::TimeFromTimespec(t.MakeAbsTimespec()),
	absl::Now() + absl::Hours(100000));
	#ifndef _WIN32
	EXPECT_GT(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
	absl::Now() + absl::Hours(100000));
	#endif
	EXPECT_GT(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
	absl::Hours(100000));
	EXPECT_GT(absl::FromUnixNanos(t.MakeAbsNanos()),
	absl::Now() + absl::Hours(100000));
	EXPECT_EQ(t.InMillisecondsFromNow(),
	std::numeric_limits<KernelTimeout::DWord>::max());
	EXPECT_EQ(t.ToChronoTimePoint(),
	std::chrono::time_point<std::chrono::system_clock>::max());
	EXPECT_GE(t.ToChronoDuration(), std::chrono::nanoseconds::max());
	}

	TEST(KernelTimeout, OverflowNanos) {
	// Test what happens when KernelTimeout is constructed with an absl::Duration
	// that would overflow now_nanos + duration.
	int64_t now_nanos = absl::ToUnixNanos(absl::Now());
	int64_t limit = std::numeric_limits<int64_t>::max() - now_nanos;
	absl::Duration duration = absl::Nanoseconds(limit) + absl::Seconds(1);
	KernelTimeout t(duration);
	// Timeouts should still be far in the future.
	EXPECT_GT(absl::TimeFromTimespec(t.MakeAbsTimespec()),
	absl::Now() + absl::Hours(100000));
	#ifndef _WIN32
	EXPECT_GT(absl::TimeFromTimespec(t.MakeClockAbsoluteTimespec(CLOCK_REALTIME)),
	absl::Now() + absl::Hours(100000));
	#endif
	EXPECT_GT(absl::DurationFromTimespec(t.MakeRelativeTimespec()),
	absl::Hours(100000));
	EXPECT_GT(absl::FromUnixNanos(t.MakeAbsNanos()),
	absl::Now() + absl::Hours(100000));
	EXPECT_LE(absl::Milliseconds(t.InMillisecondsFromNow()) - duration,
	absl::Milliseconds(5));
	EXPECT_GT(t.ToChronoTimePoint(),
	std::chrono::system_clock::now() + std::chrono::hours(100000));
	EXPECT_GT(t.ToChronoDuration(), std::chrono::hours(100000));
	}

	} // namespace