crashpad/util/misc/clock_test.cc
Mark Mentovai 281be63d00 Standardize on static constexpr for arrays when possible
This uses “static” at function scope to avoid making local copies, even
in cases where the compiler can’t see that the local copy is
unnecessary. “constexpr” adds additional safety in that it prevents
global state from being initialized from any runtime dependencies, which
would be undesirable.

At namespace scope, “constexpr” is also used where appropriate.

For the most part, this was a mechanical transformation for things
matching '(^| )const [^=]*\['.

Similar transformations could be applied to non-arrays in some cases,
but there’s limited practical impact in most non-array cases relative to
arrays, there are far more use sites, and much more manual intervention
would be required.

Change-Id: I3513b739ee8b0be026f8285475cddc5f9cc81152
Reviewed-on: https://chromium-review.googlesource.com/583997
Commit-Queue: Mark Mentovai <mark@chromium.org>
Reviewed-by: Leonard Mosescu <mosescu@chromium.org>
2017-07-25 17:40:51 +00:00

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// Copyright 2014 The Crashpad Authors. All rights reserved.
//
// 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 "util/misc/clock.h"
#include <sys/types.h>
#include <algorithm>
#include "base/format_macros.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/strings/stringprintf.h"
#include "gtest/gtest.h"
namespace crashpad {
namespace test {
namespace {
TEST(Clock, ClockMonotonicNanoseconds) {
uint64_t start = ClockMonotonicNanoseconds();
EXPECT_GT(start, 0u);
uint64_t now = start;
for (size_t iteration = 0; iteration < 10; ++iteration) {
uint64_t last = now;
now = ClockMonotonicNanoseconds();
// Use EXPECT_GE instead of EXPECT_GT, because there are no guarantees about
// the clocks resolution.
EXPECT_GE(now, last);
}
#if !defined(OS_WIN) // No SleepNanoseconds implemented on Windows.
// SleepNanoseconds() should sleep for at least the value of the clocks
// resolution, so the clocks value should definitely increase after a sleep.
// EXPECT_GT can be used instead of EXPECT_GE after the sleep.
SleepNanoseconds(1);
now = ClockMonotonicNanoseconds();
EXPECT_GT(now, start);
#endif // OS_WIN
}
#if !defined(OS_WIN) // No SleepNanoseconds implemented on Windows.
void TestSleepNanoseconds(uint64_t nanoseconds) {
uint64_t start = ClockMonotonicNanoseconds();
SleepNanoseconds(nanoseconds);
uint64_t end = ClockMonotonicNanoseconds();
uint64_t diff = end - start;
// |nanoseconds| is the lower bound for the actual amount of time spent
// sleeping.
EXPECT_GE(diff, nanoseconds);
// Its difficult to set an upper bound for the time spent sleeping, and
// attempting to do so results in a flaky test.
}
TEST(Clock, SleepNanoseconds) {
static constexpr uint64_t kTestData[] = {
0,
1,
static_cast<uint64_t>(1E3), // 1 microsecond
static_cast<uint64_t>(1E4), // 10 microseconds
static_cast<uint64_t>(1E5), // 100 microseconds
static_cast<uint64_t>(1E6), // 1 millisecond
static_cast<uint64_t>(1E7), // 10 milliseconds
static_cast<uint64_t>(2E7), // 20 milliseconds
static_cast<uint64_t>(5E7), // 50 milliseconds
};
for (size_t index = 0; index < arraysize(kTestData); ++index) {
const uint64_t nanoseconds = kTestData[index];
SCOPED_TRACE(base::StringPrintf(
"index %zu, nanoseconds %" PRIu64, index, nanoseconds));
TestSleepNanoseconds(nanoseconds);
}
}
#endif // OS_WIN
} // namespace
} // namespace test
} // namespace crashpad