// MemoryUsage.cxx

#include "dataset_util/MemoryUsage.h"
#include "dataset_util/Text.h"
#include <string>
#include <ostream>
#include <sstream>
#include "unistd.h"

using std::string;
using std::ostream;
using std::istringstream;
using std::ostringstream;

#include <iostream>

//**********************************************************************
// Local definitions.
//**********************************************************************

namespace {

// Convert string to int.
size_t ival(string(sval)) {
  istringstream ssval(sval);
  size_t ival = 0;
  ssval >> ival;
  return ival;
}

}  // end unnamed namespace

//**********************************************************************

//**********************************************************************
// Member functions.
//**********************************************************************

// Default constructor.

MemoryUsage::MemoryUsage()
: m_pid(getpid()), m_err(0), m_total(0), m_resident(0) {
  update();
}

//**********************************************************************

// Process constructor.

MemoryUsage::MemoryUsage(pid_t pid)
: m_pid(pid), m_err(0), m_total(0), m_resident(0) {
  update();
}

//**********************************************************************

// Update.

int MemoryUsage::update() {
  ostringstream sfname;
  sfname << "/proc/" << m_pid << "/statm";
  string fname = sfname.str();
  Text tmem(fname);
  if ( tmem.size() != 1 ) {
    return m_err=1;
  }
  Text::WordList vals = Text::split(tmem.line(0));
  if ( vals.size() != 7 ) {
    return m_err=2;
  }
  size_t pagesize = getpagesize();
  if ( pagesize <= 0 ) {
    return m_err=3;
  }
  m_total = pagesize*ival(vals[0]);
  m_resident = pagesize*ival(vals[1]);
  return m_err=0;
}

//**********************************************************************

// Validity.

bool MemoryUsage::is_valid() const {
  return m_err == 0;
}

//**********************************************************************

// Error code.

int MemoryUsage::error() const {
  return m_err;
}

//**********************************************************************

// Process ID.

pid_t MemoryUsage::pid() const {
  return m_pid;
}

//**********************************************************************

// Total memory usage.

size_t MemoryUsage::total() const {
  return m_total;
}

//**********************************************************************

// Resident memory.

size_t MemoryUsage::resident() const {
  return m_resident;
}

//**********************************************************************
// Free functions.
//**********************************************************************

// Output stream.

ostream& operator<<(ostream& lhs, const MemoryUsage& rhs) {
  lhs << "Memory usage for process " << rhs.pid() << ":";
  if ( ! rhs.is_valid() ) {
    lhs << "\nINVALID: error " << rhs.error();
    return lhs;
  }
  string suffix = " KB";
  int fac = 1000;
  lhs << "\n     Total: " << rhs.total()/fac << suffix;
  lhs << "\n  Resident: " << rhs.resident()/fac << suffix;
  return lhs;
}

//**********************************************************************