tests/gauge_available_memory.cpp

// Copyright 2016 The Emscripten Authors.  All rights reserved.
// Emscripten is available under two separate licenses, the MIT license and the
// University of Illinois/NCSA Open Source License.  Both these licenses can be
// found in the LICENSE file.

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

// Without noinline, Clang optimizes this whole application to a while(1) {} infinite loop.
void * __attribute__((noinline)) leak_alloc(uint64_t i)
{
	return malloc(i);
}

int main()
{
	// Keep allocating in ~powers of two until we fail, then print out how much we got.
	uint64_t availableMemory = 0;
	uint64_t i = 0x80000000ULL;
	while(i > 4096) // Leak almost all available memory, but not the last bytes, because REPORT_RESULT() needs to malloc() a bit in order to proxy from pthread to main thread.
	{
		void *ptr = leak_alloc(i);
		printf("Alloc %llu: %p\n", i, ptr);
		if (ptr) availableMemory += i;
		else i >>= 1;
	}
	printf("Total memory available: %llu\n", availableMemory);
#ifdef REPORT_RESULT
	int result = (availableMemory > 10*1024*1024);
	REPORT_RESULT(result);
#endif
}