// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/process_util.h"

#include <sys/resource.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

#include "base/basictypes.h"
#include "base/logging.h"
#include "base/sys_info.h"

const int kMicrosecondsPerSecond = 1000000;

namespace base {

int GetCurrentProcId() {
  return getpid();
}

ProcessHandle GetCurrentProcessHandle() {
  return GetCurrentProcId();
}

int GetProcId(ProcessHandle process) {
  return process;
}

ProcessMetrics::ProcessMetrics(ProcessHandle process) : process_(process),
                                                        last_time_(0),
                                                        last_system_time_(0) {
  processor_count_ = base::SysInfo::NumberOfProcessors();
}

// static
ProcessMetrics* ProcessMetrics::CreateProcessMetrics(ProcessHandle process) {
  return new ProcessMetrics(process);
}

ProcessMetrics::~ProcessMetrics() { }

void EnableTerminationOnHeapCorruption() {
  // On POSIX, there nothing to do AFAIK.
}

void RaiseProcessToHighPriority() {
  // On POSIX, we don't actually do anything here.  We could try to nice() or
  // setpriority() or sched_getscheduler, but these all require extra rights.
}

namespace {

int64 TimeValToMicroseconds(const struct timeval& tv) {
  return tv.tv_sec * kMicrosecondsPerSecond + tv.tv_usec;
}

}

int ProcessMetrics::GetCPUUsage() {
  struct timeval now;
  struct rusage usage;

  int retval = gettimeofday(&now, NULL);
  if (retval)
    return 0;
  retval = getrusage(RUSAGE_SELF, &usage);
  if (retval)
    return 0;
  
  int64 system_time = (TimeValToMicroseconds(usage.ru_stime) +
                       TimeValToMicroseconds(usage.ru_utime)) /
                        processor_count_;
  int64 time = TimeValToMicroseconds(now);

  if ((last_system_time_ == 0) || (last_time_ == 0)) {
    // First call, just set the last values.
    last_system_time_ = system_time;
    last_time_ = time;
    return 0;
  }

  int64 system_time_delta = system_time - last_system_time_;
  int64 time_delta = time - last_time_;
  DCHECK(time_delta != 0);
  if (time_delta == 0)
    return 0;

  // We add time_delta / 2 so the result is rounded.
  int cpu = static_cast<int>((system_time_delta * 100 + time_delta / 2) /
                             time_delta);

  last_system_time_ = system_time;
  last_time_ = time;

  return cpu;
}

}  // namespace base