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/*
* Created by Joachim on 16/04/2019.
* Adapted from donated nonius code.
*
* Distributed under the Boost Software License, Version 1.0. (See accompanying
* file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
*/
// Dumb std::function implementation for consistent call overhead
#ifndef TWOBLUECUBES_CATCH_DETAIL_BENCHMARK_FUNCTION_HPP_INCLUDED
#define TWOBLUECUBES_CATCH_DETAIL_BENCHMARK_FUNCTION_HPP_INCLUDED
#include "../catch_chronometer.hpp"
#include "catch_complete_invoke.hpp"
#include "../../catch_meta.hpp"
#include <cassert>
#include <type_traits>
#include <utility>
#include <memory>
namespace Catch {
namespace Benchmark {
namespace Detail {
template <typename T>
using Decay = typename std::decay<T>::type;
template <typename T, typename U>
struct is_related
: std::is_same<Decay<T>, Decay<U>> {};
/// We need to reinvent std::function because every piece of code that might add overhead
/// in a measurement context needs to have consistent performance characteristics so that we
/// can account for it in the measurement.
/// Implementations of std::function with optimizations that aren't always applicable, like
/// small buffer optimizations, are not uncommon.
/// This is effectively an implementation of std::function without any such optimizations;
/// it may be slow, but it is consistently slow.
struct BenchmarkFunction {
private:
struct callable {
virtual void call(Chronometer meter) const = 0;
virtual callable* clone() const = 0;
virtual ~callable() = default;
};
template <typename Fun>
struct model : public callable {
model(Fun&& fun) : fun(std::move(fun)) {}
model(Fun const& fun) : fun(fun) {}
model<Fun>* clone() const override { return new model<Fun>(*this); }
void call(Chronometer meter) const override {
call(meter, is_callable<Fun(Chronometer)>());
}
void call(Chronometer meter, std::true_type) const {
fun(meter);
}
void call(Chronometer meter, std::false_type) const {
meter.measure(fun);
}
Fun fun;
};
struct do_nothing { void operator()() const {} };
template <typename T>
BenchmarkFunction(model<T>* c) : f(c) {}
public:
BenchmarkFunction()
: f(new model<do_nothing>{ {} }) {}
template <typename Fun,
typename std::enable_if<!is_related<Fun, BenchmarkFunction>::value, int>::type = 0>
BenchmarkFunction(Fun&& fun)
: f(new model<typename std::decay<Fun>::type>(std::forward<Fun>(fun))) {}
BenchmarkFunction(BenchmarkFunction&& that)
: f(std::move(that.f)) {}
BenchmarkFunction(BenchmarkFunction const& that)
: f(that.f->clone()) {}
BenchmarkFunction& operator=(BenchmarkFunction&& that) {
f = std::move(that.f);
return *this;
}
BenchmarkFunction& operator=(BenchmarkFunction const& that) {
f.reset(that.f->clone());
return *this;
}
void operator()(Chronometer meter) const { f->call(meter); }
private:
std::unique_ptr<callable> f;
};
} // namespace Detail
} // namespace Benchmark
} // namespace Catch
#endif // TWOBLUECUBES_CATCH_DETAIL_BENCHMARK_FUNCTION_HPP_INCLUDED
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