gcc_std_unordered_map.cpp

//compile: g++ -fPIC --shared --std=c++17 -O4 gcc_std_unordered_map.cpp -o libgcc_std_unordered_map.so
#include <unordered_map>
#include <string_view>


#if defined(_WIN32)
#include <windows.h>
#include <psapi.h>

#elif defined(__unix__) || defined(__unix) || defined(unix) || (defined(__APPLE__) && defined(__MACH__))
#include <unistd.h>
#include <sys/resource.h>

#if defined(__APPLE__) && defined(__MACH__)
#include <mach/mach.h>

#elif (defined(_AIX) || defined(__TOS__AIX__)) || (defined(__sun__) || defined(__sun) || defined(sun) && (defined(__SVR4) || defined(__svr4__)))
#include <fcntl.h>
#include <procfs.h>

#elif defined(__linux__) || defined(__linux) || defined(linux) || defined(__gnu_linux__)
#include <stdio.h>

#endif

#else
#error "Cannot define getPeakRSS( ) or getCurrentRSS( ) for an unknown OS."
#endif


using namespace std;
typedef unordered_map<string_view, void*> Map;


size_t initialRSS = 0;
size_t getCurrentRSS( );

extern "C"{
  
void* createMap() {
  if (initialRSS == 0) initialRSS = getCurrentRSS();
  Map* map = new Map;
  //map->max_load_factor(0.5);
  return map;
}
void add(Map* map, char* str, ssize_t len, void* data){
  (*map)[string_view(str, len)] = data;
}
void* get(Map* map, char* str, ssize_t len){
  return (*map)[string_view(str, len)];
}
int contains(Map* map, char* str, ssize_t len){
  if ((*map).find(string_view(str, len)) != map->end()) return -1;
  else return 0;
}
ssize_t getMemoryUsage(){
  size_t rss = getCurrentRSS();
  if (rss < initialRSS) return 0;
  return rss - initialRSS;
}
void freeMap(void* map) {
  delete (Map*)map;
  initialRSS = 0;
}


//from David Robert Nadeau, https://github.com/martinus/map_benchmark/blob/master/src/app/getRSS.cpp




}




/**
 * Returns the current resident set size (physical memory use) measured
 * in bytes, or zero if the value cannot be determined on this OS.
 */
size_t getCurrentRSS( )
{
#if defined(_WIN32)
	/* Windows -------------------------------------------------- */
	PROCESS_MEMORY_COUNTERS info;
	GetProcessMemoryInfo( GetCurrentProcess( ), &info, sizeof(info) );
	return (size_t)info.WorkingSetSize;

#elif defined(__APPLE__) && defined(__MACH__)
	/* OSX ------------------------------------------------------ */
	struct mach_task_basic_info info;
	mach_msg_type_number_t infoCount = MACH_TASK_BASIC_INFO_COUNT;
	if ( task_info( mach_task_self( ), MACH_TASK_BASIC_INFO,
		(task_info_t)&info, &infoCount ) != KERN_SUCCESS )
		return (size_t)0L;		/* Can't access? */
	return (size_t)info.resident_size;

#elif defined(__linux__) || defined(__linux) || defined(linux) || defined(__gnu_linux__)
	/* Linux ---------------------------------------------------- */
	long rss = 0L;
	FILE* fp = NULL;
	if ( (fp = fopen( "/proc/self/statm", "r" )) == NULL )
		return (size_t)0L;		/* Can't open? */
	if ( fscanf( fp, "%*s%ld", &rss ) != 1 )
	{
		fclose( fp );
		return (size_t)0L;		/* Can't read? */
	}
	fclose( fp );
	return (size_t)rss * (size_t)sysconf( _SC_PAGESIZE);

#else
	/* AIX, BSD, Solaris, and Unknown OS ------------------------ */
	return (size_t)0L;			/* Unsupported. */
#endif
}

/**
 * Returns the peak (maximum so far) resident set size (physical
 * memory use) measured in bytes, or zero if the value cannot be
 * determined on this OS.
 */
size_t getPeakRSS( )
{
#if defined(_WIN32)
	/* Windows -------------------------------------------------- */
	PROCESS_MEMORY_COUNTERS info;
	GetProcessMemoryInfo( GetCurrentProcess( ), &info, sizeof(info) );
	return (size_t)info.PeakWorkingSetSize;

#elif (defined(_AIX) || defined(__TOS__AIX__)) || (defined(__sun__) || defined(__sun) || defined(sun) && (defined(__SVR4) || defined(__svr4__)))
	/* AIX and Solaris ------------------------------------------ */
	struct psinfo psinfo;
	int fd = -1;
	if ( (fd = open( "/proc/self/psinfo", O_RDONLY )) == -1 )
		return (size_t)0L;		/* Can't open? */
	if ( read( fd, &psinfo, sizeof(psinfo) ) != sizeof(psinfo) )
	{
		close( fd );
		return (size_t)0L;		/* Can't read? */
	}
	close( fd );
	return (size_t)(psinfo.pr_rssize * 1024L);

#elif defined(__unix__) || defined(__unix) || defined(unix) || (defined(__APPLE__) && defined(__MACH__))
	/* BSD, Linux, and OSX -------------------------------------- */
	struct rusage rusage;
	getrusage( RUSAGE_SELF, &rusage );
#if defined(__APPLE__) && defined(__MACH__)
	return (size_t)rusage.ru_maxrss;
#else
	return (size_t)(rusage.ru_maxrss * 1024L);
#endif

#else
	/* Unknown OS ----------------------------------------------- */
	return (size_t)0L;			/* Unsupported. */
#endif
}