Permalink
546 lines (484 sloc) 17.8 KB
/*
* Copyright 2017 Facebook, Inc.
*
* 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.
*/
#pragma once
#include <folly/Portability.h>
#include <folly/Preprocessor.h> // for FB_ANONYMOUS_VARIABLE
#include <folly/ScopeGuard.h>
#include <folly/Traits.h>
#include <folly/portability/GFlags.h>
#include <cassert>
#include <chrono>
#include <functional>
#include <limits>
#include <type_traits>
#include <boost/function_types/function_arity.hpp>
#include <glog/logging.h>
DECLARE_bool(benchmark);
namespace folly {
/**
* Runs all benchmarks defined. Usually put in main().
*/
void runBenchmarks();
/**
* Runs all benchmarks defined if and only if the --benchmark flag has
* been passed to the program. Usually put in main().
*/
inline bool runBenchmarksOnFlag() {
if (FLAGS_benchmark) {
runBenchmarks();
}
return FLAGS_benchmark;
}
namespace detail {
using TimeIterPair =
std::pair<std::chrono::high_resolution_clock::duration, unsigned int>;
/**
* Adds a benchmark wrapped in a std::function. Only used
* internally. Pass by value is intentional.
*/
void addBenchmarkImpl(const char* file,
const char* name,
std::function<TimeIterPair(unsigned int)>);
} // namespace detail
/**
* Supporting type for BENCHMARK_SUSPEND defined below.
*/
struct BenchmarkSuspender {
using Clock = std::chrono::high_resolution_clock;
using TimePoint = Clock::time_point;
using Duration = Clock::duration;
BenchmarkSuspender() {
start = Clock::now();
}
BenchmarkSuspender(const BenchmarkSuspender &) = delete;
BenchmarkSuspender(BenchmarkSuspender && rhs) noexcept {
start = rhs.start;
rhs.start = {};
}
BenchmarkSuspender& operator=(const BenchmarkSuspender &) = delete;
BenchmarkSuspender& operator=(BenchmarkSuspender && rhs) {
if (start != TimePoint{}) {
tally();
}
start = rhs.start;
rhs.start = {};
return *this;
}
~BenchmarkSuspender() {
if (start != TimePoint{}) {
tally();
}
}
void dismiss() {
assert(start != TimePoint{});
tally();
start = {};
}
void rehire() {
assert(start == TimePoint{});
start = Clock::now();
}
template <class F>
auto dismissing(F f) -> typename std::result_of<F()>::type {
SCOPE_EXIT { rehire(); };
dismiss();
return f();
}
/**
* This is for use inside of if-conditions, used in BENCHMARK macros.
* If-conditions bypass the explicit on operator bool.
*/
explicit operator bool() const {
return false;
}
/**
* Accumulates time spent outside benchmark.
*/
static Duration timeSpent;
private:
void tally() {
auto end = Clock::now();
timeSpent += end - start;
start = end;
}
TimePoint start;
};
/**
* Adds a benchmark. Usually not called directly but instead through
* the macro BENCHMARK defined below. The lambda function involved
* must take exactly one parameter of type unsigned, and the benchmark
* uses it with counter semantics (iteration occurs inside the
* function).
*/
template <typename Lambda>
typename std::enable_if<
boost::function_types::function_arity<decltype(&Lambda::operator())>::value
== 2
>::type
addBenchmark(const char* file, const char* name, Lambda&& lambda) {
auto execute = [=](unsigned int times) {
BenchmarkSuspender::timeSpent = {};
unsigned int niter;
// CORE MEASUREMENT STARTS
auto start = std::chrono::high_resolution_clock::now();
niter = lambda(times);
auto end = std::chrono::high_resolution_clock::now();
// CORE MEASUREMENT ENDS
return detail::TimeIterPair(
(end - start) - BenchmarkSuspender::timeSpent, niter);
};
detail::addBenchmarkImpl(file, name,
std::function<detail::TimeIterPair(unsigned int)>(execute));
}
/**
* Adds a benchmark. Usually not called directly but instead through
* the macro BENCHMARK defined below. The lambda function involved
* must take zero parameters, and the benchmark calls it repeatedly
* (iteration occurs outside the function).
*/
template <typename Lambda>
typename std::enable_if<
boost::function_types::function_arity<decltype(&Lambda::operator())>::value
== 1
>::type
addBenchmark(const char* file, const char* name, Lambda&& lambda) {
addBenchmark(file, name, [=](unsigned int times) {
unsigned int niter = 0;
while (times-- > 0) {
niter += lambda();
}
return niter;
});
}
/**
* Call doNotOptimizeAway(var) to ensure that var will be computed even
* post-optimization. Use it for variables that are computed during
* benchmarking but otherwise are useless. The compiler tends to do a
* good job at eliminating unused variables, and this function fools it
* into thinking var is in fact needed.
*
* Call makeUnpredictable(var) when you don't want the optimizer to use
* its knowledge of var to shape the following code. This is useful
* when constant propagation or power reduction is possible during your
* benchmark but not in real use cases.
*/
#ifdef _MSC_VER
#pragma optimize("", off)
inline void doNotOptimizeDependencySink(const void*) {}
#pragma optimize("", on)
template <class T>
void doNotOptimizeAway(const T& datum) {
doNotOptimizeDependencySink(&datum);
}
template <typename T>
void makeUnpredictable(T& datum) {
doNotOptimizeDependencySink(&datum);
}
#else
namespace detail {
template <typename T>
struct DoNotOptimizeAwayNeedsIndirect {
using Decayed = typename std::decay<T>::type;
// First two constraints ensure it can be an "r" operand.
// std::is_pointer check is because callers seem to expect that
// doNotOptimizeAway(&x) is equivalent to doNotOptimizeAway(x).
constexpr static bool value = !folly::IsTriviallyCopyable<Decayed>::value ||
sizeof(Decayed) > sizeof(long) || std::is_pointer<Decayed>::value;
};
} // namespace detail
template <typename T>
auto doNotOptimizeAway(const T& datum) -> typename std::enable_if<
!detail::DoNotOptimizeAwayNeedsIndirect<T>::value>::type {
// The "r" constraint forces the compiler to make datum available
// in a register to the asm block, which means that it must have
// computed/loaded it. We use this path for things that are <=
// sizeof(long) (they have to fit), trivial (otherwise the compiler
// doesn't want to put them in a register), and not a pointer (because
// doNotOptimizeAway(&foo) would otherwise be a foot gun that didn't
// necessarily compute foo).
//
// An earlier version of this method had a more permissive input operand
// constraint, but that caused unnecessary variation between clang and
// gcc benchmarks.
asm volatile("" ::"r"(datum));
}
template <typename T>
auto doNotOptimizeAway(const T& datum) -> typename std::enable_if<
detail::DoNotOptimizeAwayNeedsIndirect<T>::value>::type {
// This version of doNotOptimizeAway tells the compiler that the asm
// block will read datum from memory, and that in addition it might read
// or write from any memory location. If the memory clobber could be
// separated into input and output that would be preferrable.
asm volatile("" ::"m"(datum) : "memory");
}
template <typename T>
auto makeUnpredictable(T& datum) -> typename std::enable_if<
!detail::DoNotOptimizeAwayNeedsIndirect<T>::value>::type {
asm volatile("" : "+r"(datum));
}
template <typename T>
auto makeUnpredictable(T& datum) -> typename std::enable_if<
detail::DoNotOptimizeAwayNeedsIndirect<T>::value>::type {
asm volatile("" ::"m"(datum) : "memory");
}
#endif
} // namespace folly
/**
* Introduces a benchmark function. Used internally, see BENCHMARK and
* friends below.
*/
#define BENCHMARK_IMPL(funName, stringName, rv, paramType, paramName) \
static void funName(paramType); \
static bool FB_ANONYMOUS_VARIABLE(follyBenchmarkUnused) = ( \
::folly::addBenchmark(__FILE__, stringName, \
[](paramType paramName) -> unsigned { funName(paramName); \
return rv; }), \
true); \
static void funName(paramType paramName)
/**
* Introduces a benchmark function with support for returning the actual
* number of iterations. Used internally, see BENCHMARK_MULTI and friends
* below.
*/
#define BENCHMARK_MULTI_IMPL(funName, stringName, paramType, paramName) \
static unsigned funName(paramType); \
static bool FB_ANONYMOUS_VARIABLE(follyBenchmarkUnused) = ( \
::folly::addBenchmark(__FILE__, stringName, \
[](paramType paramName) { return funName(paramName); }), \
true); \
static unsigned funName(paramType paramName)
/**
* Introduces a benchmark function. Use with either one or two arguments.
* The first is the name of the benchmark. Use something descriptive, such
* as insertVectorBegin. The second argument may be missing, or could be a
* symbolic counter. The counter dictates how many internal iteration the
* benchmark does. Example:
*
* BENCHMARK(vectorPushBack) {
* vector<int> v;
* v.push_back(42);
* }
*
* BENCHMARK(insertVectorBegin, n) {
* vector<int> v;
* FOR_EACH_RANGE (i, 0, n) {
* v.insert(v.begin(), 42);
* }
* }
*/
#define BENCHMARK(name, ...) \
BENCHMARK_IMPL( \
name, \
FB_STRINGIZE(name), \
FB_ARG_2_OR_1(1, ## __VA_ARGS__), \
FB_ONE_OR_NONE(unsigned, ## __VA_ARGS__), \
__VA_ARGS__)
/**
* Like BENCHMARK above, but allows the user to return the actual
* number of iterations executed in the function body. This can be
* useful if the benchmark function doesn't know upfront how many
* iterations it's going to run or if it runs through a certain
* number of test cases, e.g.:
*
* BENCHMARK_MULTI(benchmarkSomething) {
* std::vector<int> testCases { 0, 1, 1, 2, 3, 5 };
* for (int c : testCases) {
* doSomething(c);
* }
* return testCases.size();
* }
*/
#define BENCHMARK_MULTI(name, ...) \
BENCHMARK_MULTI_IMPL( \
name, \
FB_STRINGIZE(name), \
FB_ONE_OR_NONE(unsigned, ## __VA_ARGS__), \
__VA_ARGS__)
/**
* Defines a benchmark that passes a parameter to another one. This is
* common for benchmarks that need a "problem size" in addition to
* "number of iterations". Consider:
*
* void pushBack(uint n, size_t initialSize) {
* vector<int> v;
* BENCHMARK_SUSPEND {
* v.resize(initialSize);
* }
* FOR_EACH_RANGE (i, 0, n) {
* v.push_back(i);
* }
* }
* BENCHMARK_PARAM(pushBack, 0)
* BENCHMARK_PARAM(pushBack, 1000)
* BENCHMARK_PARAM(pushBack, 1000000)
*
* The benchmark above estimates the speed of push_back at different
* initial sizes of the vector. The framework will pass 0, 1000, and
* 1000000 for initialSize, and the iteration count for n.
*/
#define BENCHMARK_PARAM(name, param) \
BENCHMARK_NAMED_PARAM(name, param, param)
/**
* Same as BENCHMARK_PARAM, but allows one to return the actual number of
* iterations that have been run.
*/
#define BENCHMARK_PARAM_MULTI(name, param) \
BENCHMARK_NAMED_PARAM_MULTI(name, param, param)
/*
* Like BENCHMARK_PARAM(), but allows a custom name to be specified for each
* parameter, rather than using the parameter value.
*
* Useful when the parameter value is not a valid token for string pasting,
* of when you want to specify multiple parameter arguments.
*
* For example:
*
* void addValue(uint n, int64_t bucketSize, int64_t min, int64_t max) {
* Histogram<int64_t> hist(bucketSize, min, max);
* int64_t num = min;
* FOR_EACH_RANGE (i, 0, n) {
* hist.addValue(num);
* ++num;
* if (num > max) { num = min; }
* }
* }
*
* BENCHMARK_NAMED_PARAM(addValue, 0_to_100, 1, 0, 100)
* BENCHMARK_NAMED_PARAM(addValue, 0_to_1000, 10, 0, 1000)
* BENCHMARK_NAMED_PARAM(addValue, 5k_to_20k, 250, 5000, 20000)
*/
#define BENCHMARK_NAMED_PARAM(name, param_name, ...) \
BENCHMARK_IMPL( \
FB_CONCATENATE(name, FB_CONCATENATE(_, param_name)), \
FB_STRINGIZE(name) "(" FB_STRINGIZE(param_name) ")", \
iters, \
unsigned, \
iters) { \
name(iters, ## __VA_ARGS__); \
}
/**
* Same as BENCHMARK_NAMED_PARAM, but allows one to return the actual number
* of iterations that have been run.
*/
#define BENCHMARK_NAMED_PARAM_MULTI(name, param_name, ...) \
BENCHMARK_MULTI_IMPL( \
FB_CONCATENATE(name, FB_CONCATENATE(_, param_name)), \
FB_STRINGIZE(name) "(" FB_STRINGIZE(param_name) ")", \
unsigned, \
iters) { \
return name(iters, ## __VA_ARGS__); \
}
/**
* Just like BENCHMARK, but prints the time relative to a
* baseline. The baseline is the most recent BENCHMARK() seen in
* the current scope. Example:
*
* // This is the baseline
* BENCHMARK(insertVectorBegin, n) {
* vector<int> v;
* FOR_EACH_RANGE (i, 0, n) {
* v.insert(v.begin(), 42);
* }
* }
*
* BENCHMARK_RELATIVE(insertListBegin, n) {
* list<int> s;
* FOR_EACH_RANGE (i, 0, n) {
* s.insert(s.begin(), 42);
* }
* }
*
* Any number of relative benchmark can be associated with a
* baseline. Another BENCHMARK() occurrence effectively establishes a
* new baseline.
*/
#define BENCHMARK_RELATIVE(name, ...) \
BENCHMARK_IMPL( \
name, \
"%" FB_STRINGIZE(name), \
FB_ARG_2_OR_1(1, ## __VA_ARGS__), \
FB_ONE_OR_NONE(unsigned, ## __VA_ARGS__), \
__VA_ARGS__)
/**
* Same as BENCHMARK_RELATIVE, but allows one to return the actual number
* of iterations that have been run.
*/
#define BENCHMARK_RELATIVE_MULTI(name, ...) \
BENCHMARK_MULTI_IMPL( \
name, \
"%" FB_STRINGIZE(name), \
FB_ONE_OR_NONE(unsigned, ## __VA_ARGS__), \
__VA_ARGS__)
/**
* A combination of BENCHMARK_RELATIVE and BENCHMARK_PARAM.
*/
#define BENCHMARK_RELATIVE_PARAM(name, param) \
BENCHMARK_RELATIVE_NAMED_PARAM(name, param, param)
/**
* Same as BENCHMARK_RELATIVE_PARAM, but allows one to return the actual
* number of iterations that have been run.
*/
#define BENCHMARK_RELATIVE_PARAM_MULTI(name, param) \
BENCHMARK_RELATIVE_NAMED_PARAM_MULTI(name, param, param)
/**
* A combination of BENCHMARK_RELATIVE and BENCHMARK_NAMED_PARAM.
*/
#define BENCHMARK_RELATIVE_NAMED_PARAM(name, param_name, ...) \
BENCHMARK_IMPL( \
FB_CONCATENATE(name, FB_CONCATENATE(_, param_name)), \
"%" FB_STRINGIZE(name) "(" FB_STRINGIZE(param_name) ")", \
iters, \
unsigned, \
iters) { \
name(iters, ## __VA_ARGS__); \
}
/**
* Same as BENCHMARK_RELATIVE_NAMED_PARAM, but allows one to return the
* actual number of iterations that have been run.
*/
#define BENCHMARK_RELATIVE_NAMED_PARAM_MULTI(name, param_name, ...) \
BENCHMARK_MULTI_IMPL( \
FB_CONCATENATE(name, FB_CONCATENATE(_, param_name)), \
"%" FB_STRINGIZE(name) "(" FB_STRINGIZE(param_name) ")", \
unsigned, \
iters) { \
return name(iters, ## __VA_ARGS__); \
}
/**
* Draws a line of dashes.
*/
#define BENCHMARK_DRAW_LINE() \
static bool FB_ANONYMOUS_VARIABLE(follyBenchmarkUnused) = ( \
::folly::addBenchmark(__FILE__, "-", []() -> unsigned { return 0; }), \
true);
/**
* Allows execution of code that doesn't count torward the benchmark's
* time budget. Example:
*
* BENCHMARK_START_GROUP(insertVectorBegin, n) {
* vector<int> v;
* BENCHMARK_SUSPEND {
* v.reserve(n);
* }
* FOR_EACH_RANGE (i, 0, n) {
* v.insert(v.begin(), 42);
* }
* }
*/
#define BENCHMARK_SUSPEND \
if (auto FB_ANONYMOUS_VARIABLE(BENCHMARK_SUSPEND) = \
::folly::BenchmarkSuspender()) {} \
else