/***************************************************************************************[System.cc]
 Copyright (c) 2003-2006, Niklas Een, Niklas Sorensson
 Copyright (c) 2007-2010, Niklas Sorensson

 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
 associated documentation files (the "Software"), to deal in the Software without restriction,
 including without limitation the rights to use, copy, modify, merge, publish, distribute,
 sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:

 The above copyright notice and this permission notice shall be included in all copies or
 substantial portions of the Software.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
 NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
 DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
 OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 **************************************************************************************************/

#include "monosat/utils/System.h"
#include <stdexcept>

#if defined(__linux__)

#include <cstdio>
#include <cstdlib>

using namespace Monosat;

// TODO: split the memory reading functions into two: one for reading high-watermark of RSS, and
// one for reading the current virtual memory size.

static inline int memReadStat(int field){
    char name[256];
    pid_t pid = getpid();
    int value;

    sprintf(name, "/proc/%d/statm", pid);
    FILE* in = fopen(name, "rb");
    if(in == nullptr)
        return 0;

    for(; field >= 0; field--)
        if(fscanf(in, "%d", &value) != 1){
            throw std::runtime_error("Failed to parse memory statistics from \"/proc\".\n");
        }
    fclose(in);
    return value;
}

static inline int memReadPeak(void){
    char name[256];
    pid_t pid = getpid();

    sprintf(name, "/proc/%d/status", pid);
    FILE* in = fopen(name, "rb");
    if(in == nullptr)
        return 0;

    // Find the correct line, beginning with "VmPeak:":
    int peak_kb = 0;
    while(!feof(in) && fscanf(in, "VmPeak: %d kB", &peak_kb) != 1)
        while(!feof(in) && fgetc(in) != '\n');
    fclose(in);

    return peak_kb;
}

double Monosat::memUsed(){
    return (double) memReadStat(0) * (double) getpagesize() / (1024 * 1024);
}

double Monosat::memUsedPeak(){
    double peak = memReadPeak() / 1024.0;
    return peak == 0 ? memUsed() : peak;
}

#elif defined(__FreeBSD__)

double Monosat::memUsed(void) {
    struct rusage ru;
    getrusage(RUSAGE_SELF, &ru);
    return (double)ru.ru_maxrss / 1024.0;}
double Monosat::memUsedPeak(void) {return memUsed();}

#elif defined(__APPLE__)
#include <malloc/malloc.h>

double Monosat::memUsed(void) {
    malloc_statistics_t t;
    malloc_zone_statistics(NULL, &t);
    return (double)t.max_size_in_use / (1024*1024);}
    double Monosat::memUsedPeak(void) {return memUsed(); }
#else
double Monosat::memUsed() {
    return 0;}
double Monosat::memUsedPeak() {
    return 0;}
#endif
