factor/vm/sampling_profiler.cpp

#include "master.hpp"

namespace factor
{

profiling_sample::profiling_sample(factor_vm *vm,
	fixnum sample_count,
	fixnum gc_sample_count,
	fixnum foreign_sample_count,
	fixnum foreign_thread_sample_count,
	context *ctx)
	:
	sample_count(sample_count),
	gc_sample_count(gc_sample_count),
	foreign_sample_count(foreign_sample_count),
	foreign_thread_sample_count(foreign_thread_sample_count),
	ctx(ctx)
{
	vm->record_callstack_sample(&callstack_begin, &callstack_end);
}

void factor_vm::record_sample()
{
	fixnum recorded_sample_count;
	fixnum recorded_gc_sample_count;
	fixnum recorded_foreign_sample_count;
	fixnum recorded_foreign_thread_sample_count;

	FACTOR_MEMORY_BARRIER();
	recorded_sample_count = safepoint_sample_count;
	recorded_gc_sample_count = safepoint_gc_sample_count;
	recorded_foreign_sample_count = safepoint_foreign_sample_count;
	recorded_foreign_thread_sample_count = safepoint_foreign_thread_sample_count;
	if (recorded_sample_count
		+ recorded_gc_sample_count
		+ recorded_foreign_sample_count
		+ recorded_foreign_thread_sample_count
		== 0)
		return;

	/* Another sample signal could be raised while we record these counts */
	FACTOR_ATOMIC_SUB(&safepoint_sample_count, recorded_sample_count);
	FACTOR_ATOMIC_SUB(&safepoint_gc_sample_count, recorded_gc_sample_count);
	FACTOR_ATOMIC_SUB(&safepoint_foreign_sample_count, recorded_foreign_sample_count);
	FACTOR_ATOMIC_SUB(&safepoint_foreign_thread_sample_count, recorded_foreign_thread_sample_count);

	samples.push_back(profiling_sample(
		this,
		recorded_sample_count,
		recorded_gc_sample_count,
		recorded_foreign_sample_count,
		recorded_foreign_thread_sample_count,
		ctx
	));
}

void factor_vm::record_callstack_sample(cell *begin, cell *end)
{
	*begin = sample_callstacks.size();
	stack_frame *frame = ctx->bottom_frame();

	while (frame >= ctx->callstack_top) {
		sample_callstacks.push_back(frame_code(frame));
		frame = frame_successor(frame);
	}

	*end = sample_callstacks.size();
}

void factor_vm::set_sampling_profiler(bool sampling_p)
{
	if (sampling_p == sampling_profiler_p)
		return;
	
	if (sampling_p)
		start_sampling_profiler();
	else
		end_sampling_profiler();
}

void factor_vm::clear_samples()
{
	// Swapping into temporaries releases the vector's allocated storage,
	// whereas clear() would leave the allocation as-is
	std::vector<profiling_sample> sample_graveyard;
	std::vector<code_block*> sample_callstack_graveyard;
	samples.swap(sample_graveyard);
	sample_callstacks.swap(sample_callstack_graveyard);
}

void factor_vm::start_sampling_profiler()
{
	safepoint_sample_count = 0;
	safepoint_gc_sample_count = 0;
	safepoint_foreign_sample_count = 0;
	safepoint_foreign_thread_sample_count = 0;
	clear_samples();
	samples.reserve(10*FACTOR_PROFILE_SAMPLES_PER_SECOND);
	sample_callstacks.reserve(100*FACTOR_PROFILE_SAMPLES_PER_SECOND);
	sampling_profiler_p = true;
	start_sampling_profiler_timer();
}

void factor_vm::end_sampling_profiler()
{
	sampling_profiler_p = false;
	FACTOR_MEMORY_BARRIER();
	end_sampling_profiler_timer();
	record_sample();
}

void factor_vm::primitive_sampling_profiler()
{
	set_sampling_profiler(to_boolean(ctx->pop()));
}

void factor_vm::primitive_get_samples()
{
	if (sampling_profiler_p || samples.empty()) {
		ctx->push(false_object);
	} else {
		data_root<array> samples_array(allot_array(samples.size(), false_object),this);
		std::vector<profiling_sample>::const_iterator from_iter = samples.begin();
		cell to_i = 0;

		for (; from_iter != samples.end(); ++from_iter, ++to_i)
		{
			data_root<array> sample(allot_array(6, false_object),this);

			set_array_nth(sample.untagged(),0,from_unsigned_cell(from_iter->sample_count));
			set_array_nth(sample.untagged(),1,from_unsigned_cell(from_iter->gc_sample_count));
			set_array_nth(sample.untagged(),2,from_unsigned_cell(from_iter->foreign_sample_count));
			set_array_nth(sample.untagged(),3,from_unsigned_cell(from_iter->foreign_thread_sample_count));
			set_array_nth(sample.untagged(),4,allot_alien((void*)from_iter->ctx));

			cell callstack_size = from_iter->callstack_end - from_iter->callstack_begin;
			data_root<array> callstack(allot_array(callstack_size,false_object),this);

			std::vector<code_block*>::const_iterator
				callstacks_begin = sample_callstacks.begin(),
				c_from_iter = callstacks_begin + from_iter->callstack_begin,
				c_from_iter_end = callstacks_begin + from_iter->callstack_end;
			cell c_to_i = 0;

			for (; c_from_iter != c_from_iter_end; ++c_from_iter, ++c_to_i)
				set_array_nth(callstack.untagged(),c_to_i,(*c_from_iter)->owner);

			set_array_nth(sample.untagged(),5,callstack.value());

			set_array_nth(samples_array.untagged(),to_i,sample.value());
		}
		ctx->push(samples_array.value());
	}
}

void factor_vm::primitive_clear_samples()
{
	clear_samples();
}

}