react-native/ReactCommon/microprofiler/MicroProfiler.h

83 lines
2.7 KiB
C++

// Copyright (c) Facebook, Inc. and its affiliates.
// This source code is licensed under the MIT license found in the
// LICENSE file in the root directory of this source tree.
#pragma once
#include <atomic>
#include <thread>
// #define WITH_MICRO_PROFILER 1
#ifdef WITH_MICRO_PROFILER
#define MICRO_PROFILER_SECTION(name) MicroProfilerSection __b(name)
#define MICRO_PROFILER_SECTION_NAMED(var_name, name) MicroProfilerSection var_name(name)
#else
#define MICRO_PROFILER_SECTION(name)
#define MICRO_PROFILER_SECTION_NAMED(var_name, name)
#endif
namespace facebook {
namespace react {
enum MicroProfilerName {
__INTERNAL_BENCHMARK_INNER,
__INTERNAL_BENCHMARK_OUTER,
__LENGTH__,
};
/**
* MicroProfiler is a performance profiler for measuring the cumulative impact of
* a large number of small-ish calls. This is normally a problem for standard profilers
* like Systrace because the overhead of the profiler itself skews the timings you
* are able to collect. This is especially a problem when doing nested calls to
* profiled functions, as the parent calls will contain the overhead of their profiling
* plus the overhead of all their childrens' profiling.
*
* MicroProfiler attempts to be low overhead by 1) aggregating timings in memory and
* 2) trying to remove estimated profiling overhead from the returned timings.
*
* To remove estimated overhead, at the beginning of each trace we calculate the
* average cost of profiling a no-op code section, as well as invoking the average
* cost of invoking the system clock. The former is subtracted out for each child
* profiler section that is invoked within a parent profiler section. The latter is
* subtracted from each section, child or not.
*
* After MicroProfiler::stopProfiling() is called, a table of tracing data is emitted
* to glog (which shows up in logcat on Android).
*/
struct MicroProfiler {
static const char* profilingNameToString(MicroProfilerName name) {
switch (name) {
case __INTERNAL_BENCHMARK_INNER:
return "__INTERNAL_BENCHMARK_INNER";
case __INTERNAL_BENCHMARK_OUTER:
return "__INTERNAL_BENCHMARK_OUTER";
case __LENGTH__:
throw std::runtime_error("__LENGTH__ has no name");
default:
throw std::runtime_error("Trying to convert unknown MicroProfilerName to string");
}
}
static void startProfiling();
static void stopProfiling();
static bool isProfiling();
static void runInternalBenchmark();
};
class MicroProfilerSection {
public:
MicroProfilerSection(MicroProfilerName name);
~MicroProfilerSection();
private:
bool isProfiling_;
MicroProfilerName name_;
uint_fast64_t startTime_;
uint_fast32_t startNumProfileSections_;
};
} }