faux-folly/folly/test/function_benchmark/main.cpp

/*
 * Copyright 2015 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.
 */

#include <folly/test/function_benchmark/benchmark_impl.h>
#include <folly/test/function_benchmark/test_functions.h>

#include <folly/Benchmark.h>
#include <folly/ScopeGuard.h>
#include <gflags/gflags.h>
#include <glog/logging.h>

using folly::ScopeGuard;
using folly::makeGuard;

// Declare the bm_max_iters flag from folly/Benchmark.cpp
DECLARE_int32(bm_max_iters);

// Directly invoking a function
BENCHMARK(fn_invoke, iters) {
  for (size_t n = 0; n < iters; ++n) {
    doNothing();
  }
}

// Invoking a function through a function pointer
BENCHMARK(fn_ptr_invoke, iters) {
  BM_fn_ptr_invoke_impl(iters, doNothing);
}

// Invoking a function through a std::function object
BENCHMARK(std_function_invoke, iters) {
  BM_std_function_invoke_impl(iters, doNothing);
}

// Invoking a member function through a member function pointer
BENCHMARK(mem_fn_invoke, iters) {
  TestClass tc;
  BM_mem_fn_invoke_impl(iters, &tc, &TestClass::doNothing);
}

// Invoke a function pointer through an inlined wrapper function
BENCHMARK(fn_ptr_invoke_through_inline, iters) {
  BM_fn_ptr_invoke_inlined_impl(iters, doNothing);
}

// Invoke a lambda that calls doNothing() through an inlined wrapper function
BENCHMARK(lambda_invoke_fn, iters) {
  BM_invoke_fn_template_impl(iters, [] { doNothing(); });
}

// Invoke a lambda that does nothing
BENCHMARK(lambda_noop, iters) {
  BM_invoke_fn_template_impl(iters, [] {});
}

// Invoke a lambda that modifies a local variable
BENCHMARK(lambda_local_var, iters) {
  uint32_t count1 = 0;
  uint32_t count2 = 0;
  BM_invoke_fn_template_impl(iters, [&] {
    // Do something slightly more complicated than just incrementing a
    // variable.  Otherwise gcc is smart enough to optimize the loop away.
    if (count1 & 0x1) {
      ++count2;
    }
    ++count1;
  });

  // Use the values we computed, so gcc won't optimize the loop away
  CHECK_EQ(iters, count1);
  CHECK_EQ(iters / 2, count2);
}

// Invoke a function pointer through the same wrapper used for lambdas
BENCHMARK(fn_ptr_invoke_through_template, iters) {
  BM_invoke_fn_template_impl(iters, doNothing);
}

// Invoking a virtual method
BENCHMARK(virtual_fn_invoke, iters) {
  VirtualClass vc;
  BM_virtual_fn_invoke_impl(iters, &vc);
}

// Creating a function pointer and invoking it
BENCHMARK(fn_ptr_create_invoke, iters) {
  for (size_t n = 0; n < iters; ++n) {
    void (*fn)() = doNothing;
    fn();
  }
}

// Creating a std::function object from a function pointer, and invoking it
BENCHMARK(std_function_create_invoke, iters) {
  for (size_t n = 0; n < iters; ++n) {
    std::function<void()> fn = doNothing;
    fn();
  }
}

// Creating a pointer-to-member and invoking it
BENCHMARK(mem_fn_create_invoke, iters) {
  TestClass tc;
  for (size_t n = 0; n < iters; ++n) {
    void (TestClass::*memfn)() = &TestClass::doNothing;
    (tc.*memfn)();
  }
}

// Using std::bind to create a std::function from a member function,
// and invoking it
BENCHMARK(std_bind_create_invoke, iters) {
  TestClass tc;
  for (size_t n = 0; n < iters; ++n) {
    std::function<void()> fn = std::bind(&TestClass::doNothing, &tc);
    fn();
  }
}

// Using std::bind directly to invoke a member function
BENCHMARK(std_bind_direct_invoke, iters) {
  TestClass tc;
  for (size_t n = 0; n < iters; ++n) {
    auto fn = std::bind(&TestClass::doNothing, &tc);
    fn();
  }
}

// Using ScopeGuard to invoke a std::function
BENCHMARK(scope_guard_std_function, iters) {
  std::function<void()> fn(doNothing);
  for (size_t n = 0; n < iters; ++n) {
    ScopeGuard g = makeGuard(fn);
  }
}

// Using ScopeGuard to invoke a std::function,
// but create the ScopeGuard with an rvalue to a std::function
BENCHMARK(scope_guard_std_function_rvalue, iters) {
  for (size_t n = 0; n < iters; ++n) {
    ScopeGuard g = makeGuard(std::function<void()>(doNothing));
  }
}

// Using ScopeGuard to invoke a function pointer
BENCHMARK(scope_guard_fn_ptr, iters) {
  for (size_t n = 0; n < iters; ++n) {
    ScopeGuard g = makeGuard(doNothing);
  }
}

// Using ScopeGuard to invoke a lambda that does nothing
BENCHMARK(scope_guard_lambda_noop, iters) {
  for (size_t n = 0; n < iters; ++n) {
    ScopeGuard g = makeGuard([] {});
  }
}

// Using ScopeGuard to invoke a lambda that invokes a function
BENCHMARK(scope_guard_lambda_function, iters) {
  for (size_t n = 0; n < iters; ++n) {
    ScopeGuard g = makeGuard([] { doNothing(); });
  }
}

// Using ScopeGuard to invoke a lambda that modifies a local variable
BENCHMARK(scope_guard_lambda_local_var, iters) {
  uint32_t count = 0;
  for (size_t n = 0; n < iters; ++n) {
    ScopeGuard g = makeGuard([&] {
      // Increment count if n is odd.  Without this conditional check
      // (i.e., if we just increment count each time through the loop),
      // gcc is smart enough to optimize the entire loop away, and just set
      // count = iters.
      if (n & 0x1) {
        ++count;
      }
    });
  }

  // Check that the value of count is what we expect.
  // This check is necessary: if we don't use count, gcc detects that count is
  // unused and optimizes the entire loop away.
  CHECK_EQ(iters / 2, count);
}

BENCHMARK_DRAW_LINE()

BENCHMARK(throw_exception, iters) {
  for (size_t n = 0; n < iters; ++n) {
    try {
      throwException();
    } catch (const std::exception& ex) {
    }
  }
}

BENCHMARK(catch_no_exception, iters) {
  for (size_t n = 0; n < iters; ++n) {
    try {
      doNothing();
    } catch (const std::exception& ex) {
    }
  }
}

BENCHMARK(return_exc_ptr, iters) {
  for (size_t n = 0; n < iters; ++n) {
    returnExceptionPtr();
  }
}

BENCHMARK(exc_ptr_param_return, iters) {
  for (size_t n = 0; n < iters; ++n) {
    std::exception_ptr ex;
    exceptionPtrReturnParam(&ex);
  }
}

BENCHMARK(exc_ptr_param_return_null, iters) {
  for (size_t n = 0; n < iters; ++n) {
    exceptionPtrReturnParam(nullptr);
  }
}

BENCHMARK(return_string, iters) {
  for (size_t n = 0; n < iters; ++n) {
    returnString();
  }
}

BENCHMARK(return_string_noexcept, iters) {
  for (size_t n = 0; n < iters; ++n) {
    returnStringNoExcept();
  }
}

BENCHMARK(return_code, iters) {
  for (size_t n = 0; n < iters; ++n) {
    returnCode(false);
  }
}

BENCHMARK(return_code_noexcept, iters) {
  for (size_t n = 0; n < iters; ++n) {
    returnCodeNoExcept(false);
  }
}

// main()

int main(int argc, char** argv) {
  gflags::ParseCommandLineFlags(&argc, &argv, true);
  folly::runBenchmarks();
}