Files
android_external_libcxx/utils/google-benchmark/src/sleep.h
Eric Fiselier d9b9ef75a8 [libcxx] Add support for benchmark tests using Google Benchmark.
Summary:
This patch does the following:

1. Checks in a copy of the Google Benchmark library into the libc++ repo under `utils/google-benchmark`.
2. Teaches libc++ how to build Google Benchmark against both (A) in-tree libc++ and (B) the platforms native STL.
3. Allows performance benchmarks to be built as part of the libc++ build.

Building the benchmarks (and Google Benchmark) is off by default. It must be enabled using the CMake option `-DLIBCXX_INCLUDE_BENCHMARKS=ON`. When this option is enabled the tests under `libcxx/benchmarks`  can be built using the `libcxx-benchmarks` target.

On Linux platforms where libstdc++ is the default STL the CMake option `-DLIBCXX_BUILD_BENCHMARKS_NATIVE_STDLIB=ON` can be used to build each benchmark test against libstdc++ as well. This is useful for comparing performance between standard libraries.

Support for benchmarks is currently very minimal. They must be manually run by the user and there is no mechanism for detecting performance regressions.

Known Issues:

* `-DLIBCXX_INCLUDE_BENCHMARKS=ON` is only supported for Clang, and not GCC, since the `-stdlib=libc++` option is needed to build Google Benchmark.








Reviewers: danalbert, dberlin, chandlerc, mclow.lists, jroelofs

Subscribers: chandlerc, dberlin, tberghammer, danalbert, srhines, hfinkel

Differential Revision: https://reviews.llvm.org/D22240

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@276049 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-19 23:07:03 +00:00

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C++

#ifndef BENCHMARK_SLEEP_H_
#define BENCHMARK_SLEEP_H_
#include <cstdint>
namespace benchmark {
const int64_t kNumMillisPerSecond = 1000LL;
const int64_t kNumMicrosPerMilli = 1000LL;
const int64_t kNumMicrosPerSecond = kNumMillisPerSecond * 1000LL;
const int64_t kNumNanosPerMicro = 1000LL;
const int64_t kNumNanosPerSecond = kNumNanosPerMicro * kNumMicrosPerSecond;
void SleepForMilliseconds(int milliseconds);
void SleepForSeconds(double seconds);
} // end namespace benchmark
#endif // BENCHMARK_SLEEP_H_