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// Copyright 2018 The gVisor 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
//
// http://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 <stdint.h>
#include <sys/time.h>
#include <syscall.h>
#include <time.h>
#include <unistd.h>
#include <map>
#include <string>
#include <utility>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "absl/strings/numbers.h"
#include "absl/time/clock.h"
#include "absl/time/time.h"
#include "test/util/test_util.h"
namespace gvisor {
namespace testing {
namespace {
std::string PrintClockId(::testing::TestParamInfo<clockid_t> info) {
switch (info.param) {
case CLOCK_MONOTONIC:
return "CLOCK_MONOTONIC";
case CLOCK_REALTIME:
return "CLOCK_REALTIME";
case CLOCK_BOOTTIME:
return "CLOCK_BOOTTIME";
default:
return absl::StrCat(info.param);
}
}
class CorrectVDSOClockTest : public ::testing::TestWithParam<clockid_t> {};
TEST_P(CorrectVDSOClockTest, IsCorrect) {
struct timespec tvdso, tsys;
absl::Time vdso_time, sys_time;
uint64_t total_calls = 0;
// It is expected that 82.5% of clock_gettime calls will be less than 100us
// skewed from the system time.
// Unfortunately this is not only influenced by the VDSO clock skew, but also
// by arbitrary scheduling delays and the like. The test is therefore
// regularly disabled.
std::map<absl::Duration, std::tuple<double, uint64_t, uint64_t>> confidence =
{
{absl::Microseconds(100), std::make_tuple(0.825, 0, 0)},
{absl::Microseconds(250), std::make_tuple(0.94, 0, 0)},
{absl::Milliseconds(1), std::make_tuple(0.999, 0, 0)},
};
absl::Time start = absl::Now();
while (absl::Now() < start + absl::Seconds(30)) {
EXPECT_THAT(clock_gettime(GetParam(), &tvdso), SyscallSucceeds());
EXPECT_THAT(syscall(__NR_clock_gettime, GetParam(), &tsys),
SyscallSucceeds());
vdso_time = absl::TimeFromTimespec(tvdso);
for (auto const& conf : confidence) {
std::get<1>(confidence[conf.first]) +=
(sys_time - vdso_time) < conf.first;
}
sys_time = absl::TimeFromTimespec(tsys);
for (auto const& conf : confidence) {
std::get<2>(confidence[conf.first]) +=
(vdso_time - sys_time) < conf.first;
}
++total_calls;
}
for (auto const& conf : confidence) {
EXPECT_GE(std::get<1>(conf.second) / static_cast<double>(total_calls),
std::get<0>(conf.second));
EXPECT_GE(std::get<2>(conf.second) / static_cast<double>(total_calls),
std::get<0>(conf.second));
}
}
INSTANTIATE_TEST_SUITE_P(ClockGettime, CorrectVDSOClockTest,
::testing::Values(CLOCK_MONOTONIC, CLOCK_REALTIME,
CLOCK_BOOTTIME),
PrintClockId);
} // namespace
} // namespace testing
} // namespace gvisor
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