/*
 * Author:  David Robert Nadeau
 * Site:    http://NadeauSoftware.com/
 * License: Creative Commons Attribution 3.0 Unported License
 *          http://creativecommons.org/licenses/by/3.0/deed.en_US
 *
 * Changes made by Edward Kmett in 2015:
 *
 * * Minor formatting changes.
 * * Added getHardPageFaults()
 */

#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

/**
 * 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
}


/**
 * 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
}

/** Return the number of hard page faults that have occurred. */
size_t getHardPageFaults() {
#if defined(_WIN32)
  /* Windows --------------------------------------------------

     It's not clear how to obtain the number of hard page faults
     on Windows. Taking inspiraton from GHC's getPageFaults function
     (https://gitlab.haskell.org/ghc/ghc/blob/1285d6b95fbae7858abbc4722bc2301d7fe40425/rts/win32/GetTime.c#L148-154),
     we return an extremely conservative lower bound. */
  return 0;
#else
  /* Other OSes ----------------------------------------------- */
  struct rusage rusage;
  getrusage(RUSAGE_SELF, &rusage);
  return (size_t)rusage.ru_majflt;
#endif
}