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implicit_cast<> only performs a cast in cases where an implicit conversion would be possible. It’s even safer than static_cast<> It’s an “explicit implicit” cast, which is not normally necsesary, but is frequently required when working with the ?: operator, functions like std::min() and std::max(), and logging and testing macros. The public style guide does not mention implicit_cast<> only because it is not part of the standard library, but would otherwise require it in these situations. Since base does provide implicit_cast<>, it should be used whenever possible. The only uses of static_cast<> not converted to implicit_cast<> are those that require static_cast<>, such as those that assign an integer constant to a variable of an enum type. R=rsesek@chromium.org Review URL: https://codereview.chromium.org/700383007
93 lines
2.8 KiB
C++
93 lines
2.8 KiB
C++
// Copyright 2014 The Crashpad Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "util/misc/clock.h"
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#include <stdint.h>
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#include <algorithm>
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#include "base/basictypes.h"
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#include "base/logging.h"
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#include "base/strings/stringprintf.h"
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#include "gtest/gtest.h"
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namespace crashpad {
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namespace test {
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namespace {
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TEST(Clock, ClockMonotonicNanoseconds) {
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uint64_t start = ClockMonotonicNanoseconds();
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EXPECT_GT(start, 0u);
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uint64_t now = start;
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for (size_t iteration = 0; iteration < 10; ++iteration) {
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uint64_t last = now;
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now = ClockMonotonicNanoseconds();
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// Use EXPECT_GE instead of EXPECT_GT, because there are no guarantees about
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// the clock’s resolution.
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EXPECT_GE(now, last);
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}
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// SleepNanoseconds() should sleep for at least the value of the clock’s
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// resolution, so the clock’s value should definitely increase after a sleep.
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// EXPECT_GT can be used instead of EXPECT_GE after the sleep.
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SleepNanoseconds(1);
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now = ClockMonotonicNanoseconds();
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EXPECT_GT(now, start);
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}
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void TestSleepNanoseconds(uint64_t nanoseconds) {
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uint64_t start = ClockMonotonicNanoseconds();
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SleepNanoseconds(nanoseconds);
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uint64_t end = ClockMonotonicNanoseconds();
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uint64_t diff = end - start;
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// |nanoseconds| is the lower bound for the actual amount of time spent
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// sleeping.
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EXPECT_GE(diff, nanoseconds);
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// It’s difficult to set an upper bound for the time spent sleeping, and
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// attempting to do so results in a flaky test.
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}
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TEST(Clock, SleepNanoseconds) {
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const uint64_t kTestData[] = {
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0,
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1,
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implicit_cast<uint64_t>(1E3), // 1 microsecond
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implicit_cast<uint64_t>(1E4), // 10 microseconds
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implicit_cast<uint64_t>(1E5), // 100 microseconds
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implicit_cast<uint64_t>(1E6), // 1 millisecond
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implicit_cast<uint64_t>(1E7), // 10 milliseconds
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implicit_cast<uint64_t>(2E7), // 20 milliseconds
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implicit_cast<uint64_t>(5E7), // 50 milliseconds
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};
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for (size_t index = 0; index < arraysize(kTestData); ++index) {
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const uint64_t nanoseconds = kTestData[index];
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SCOPED_TRACE(
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base::StringPrintf("index %zu, nanoseconds %llu", index, nanoseconds));
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TestSleepNanoseconds(nanoseconds);
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}
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}
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} // namespace
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} // namespace test
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} // namespace crashpad
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