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Single Header Profiling library using chrome://tracing
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Mist_Profiler
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README.md

README.md

Mist_Profiler

About:

The Mist_Profiler is a single header utility that generates chrome://tracing json that can be then imported and viewed using chrome's tracing utility. Mist_Profiler is completely thread safe and attempts to minimize contention between thread.

Usage:

Using Mist_Profiler.h is simple, Include in one of your source files with define:

	#define MIST_PROFILE_IMPLEMENTATION
	#define MIST_PROFILE_ENABLED // Must be included before all Mist_Profiler.h includes in order to allow the profiler to work.
	#include <Mist_Profiler.h>

Before profiling call:

	Mist_ProfileInit();

And at the end of your program execution call

	Mist_ProfilerTerminate();

Warning: No other calls to the profiler should be made after terminate has been invoked!

To gather samples for the profiler, simply call

	MIST_PROFILE_BEGIN("Category Of Sample", "Sample Name");

	// ...

	MIST_PROFILE_END("Category Of Sample", "Sample Name");

chrome://tracing matches these calls by name and category. Determining a unique name for these is important.

Warning: Category and Name are not stored, their lifetime must exist either until program termination or until the next call to Mist_FlushThreadBuffer and Mist_Flush.

Once a significant amount of samples have been gathered, samples have to be flushed. A simple way to do this is shown below

	// Buffers are only added to the list once they are full.
	// This minimizes contention and allows simple modification of the buffers.
	// The buffers are also stored as thread local globals, and must be flushed from their threads.
	if(Mist_ProfileListSize() == 0)
	{
		// Adds the current buffer to the list of buffers even if it hasn't been filled up yet.
		Mist_FlushThreadBuffer();
	}

	char* print;
	size_t bufferSize;
	Mist_FlushAlloc(&print, &bufferSize); // Edit: Changed from Mist_Flush!! Mist_Flush now requires a buffer to be passed to it.
	fprintf(fileHandle, "%s", print);
	free(print);

Warning: Flushing many samples can be slow, the size of the buffer can either be minimized or flushing on a seperate thread can be used to minimize the latency.

Finally, when printing out the buffer, the set of samples must include the preface and postface.

	fprintf(fileHandle, "%s", mist_ProfilePreface);
	fprintf(fileHandle, "%s", flushedSamples);
	fprintf(fileHandle, "%s", moreFlushedSamples);
	fprintf(fileHandle, "%s", mist_ProfilePostface);

Threading:

It is important to call Mist_FlushThreadBuffer() before shutting down a thread and before the last flush as the remaining buffers might have some samples left in them.

A multithreaded program could have the format:

	#define MIST_PROFILE_IMPLEMENTATION
	#include <Mist_Profiler.h>
	
	Init Profiler
	Add mist_ProfilePreface to the file

	Startup job threads
		Create samples in these threads
		At thread termination, call Mist_FlushThreadBuffer()

	Startup flushing thread
		Call Mist_ProfileListSize()
		If there are buffers, flush them to a file
		At thread termination, call Mist_FlushThreadBuffer()

	Kill all the threads
	Call Mist_FlushAlloc() to flush the remaining buffers

	Print to a file
	Add mist_ProfilePostface to the file

	Terminate the profiler
Tested Compilers
  • MSVC 2017
Supported Platforms
  • Windows
Planned Support
  • Unix
  • Mac OS
  • GCC
  • Clang

Sample Program

#include <stdlib.h>
#include <stdio.h>

#define MIST_PROFILE_IMPLEMENTATION
#include <Mist_Profiler.h>

int main(int argc, char** argv)
{
	(void)argc;
	(void)argv;

	Mist_ProfileInit();

	FILE* file;
	fopen_s(&file, "Profiling.txt", "w");

	MIST_PROFILE_BEGIN("Full Profile", "Profiling...");
	for (int i = 0; i < 1024; i++)
	{
		MIST_PROFILE_BEGIN("Profiling!", "Profiling!");
		MIST_PROFILE_END("Profiling!", "Profiling!");
		MIST_PROFILE_EVENT("Profiling!", "Event!");
	}

	MIST_PROFILE_BEGIN("Profiling!", "Flushing!");
	Mist_FlushThreadBuffer();
	char* buffer = Mist_FlushAlloc();
	MIST_PROFILE_END("Profiling!", "Flushing!");

	MIST_PROFILE_BEGIN("Profiling!", "Writing To File!");
	fprintf(file, "%s", mist_ProfilePreface);
	fprintf(file, "%s", buffer);
	free(buffer);
	MIST_PROFILE_END("Profiling!", "Writing To File!");

	MIST_PROFILE_END("Full Profile", "Profiling...");

	Mist_FlushThreadBuffer();
	buffer = Mist_FlushAlloc();

	fprintf(file, "%s", buffer);
	fprintf(file, "%s", mist_ProfilePostface);
	free(buffer);

	fclose(file);
	Mist_ProfileTerminate();
	return 0;
}
Visualized Capture:

alt text

Thanks

Big thanks to https://www.gamasutra.com/view/news/176420/Indepth_Using_Chrometracing_to_view_your_inline_profiling_data.php https://aras-p.info/blog/2017/01/23/Chrome-Tracing-as-Profiler-Frontend/ and the team working on chrome://tracing or providing the tools and information needed to implement this library.

Change Log

  • 2019-02-02: Added MIST_PROFILE_ENABLED to allow the profiler to be enabled and disabled. This makes usage a bit more cumbersome, but simplifies turning off the compiler. This will break previous usage of the compiler.
  • 2019-01-13: Changed Mist_Flush to Mist_FlushAlloc. Mist_Flush now requires an explicit buffer. This will break previous usage of the profiler.
  • 2019-01-13: Changed MIST_BEGIN/END_PROFILE to MIST_PROFILE_BEGIN/END. Will break previous calls to old macros.
  • 2018-02-14: Removed the need for a comma to append the buffers. This will break previous usage of the profiler but since it isn't a week old, I believe this is fine.
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