// Copyright (c) 2013 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/process_metrics.h"

#include <mach/mach.h>
#include <mach/mach_vm.h>
#include <mach/shared_region.h>
#include <sys/sysctl.h>

#include "base/containers/hash_tables.h"
#include "base/logging.h"
#include "base/mac/scoped_mach_port.h"
#include "base/sys_info.h"

namespace base {

namespace {

bool GetTaskInfo(mach_port_t task, task_basic_info_64* task_info_data) {
  if (task == MACH_PORT_NULL)
    return false;
  mach_msg_type_number_t count = TASK_BASIC_INFO_64_COUNT;
  kern_return_t kr = task_info(task,
                               TASK_BASIC_INFO_64,
                               reinterpret_cast<task_info_t>(task_info_data),
                               &count);
  // Most likely cause for failure: |task| is a zombie.
  return kr == KERN_SUCCESS;
}

bool GetCPUTypeForProcess(pid_t pid, cpu_type_t* cpu_type) {
  size_t len = sizeof(*cpu_type);
  int result = sysctlbyname("sysctl.proc_cputype",
                            cpu_type,
                            &len,
                            NULL,
                            0);
  if (result != 0) {
    DPLOG(ERROR) << "sysctlbyname(""sysctl.proc_cputype"")";
    return false;
  }

  return true;
}

bool IsAddressInSharedRegion(mach_vm_address_t addr, cpu_type_t type) {
  if (type == CPU_TYPE_I386) {
    return addr >= SHARED_REGION_BASE_I386 &&
           addr < (SHARED_REGION_BASE_I386 + SHARED_REGION_SIZE_I386);
  } else if (type == CPU_TYPE_X86_64) {
    return addr >= SHARED_REGION_BASE_X86_64 &&
           addr < (SHARED_REGION_BASE_X86_64 + SHARED_REGION_SIZE_X86_64);
  } else {
    return false;
  }
}

}  // namespace

// Getting a mach task from a pid for another process requires permissions in
// general, so there doesn't really seem to be a way to do these (and spinning
// up ps to fetch each stats seems dangerous to put in a base api for anyone to
// call). Child processes ipc their port, so return something if available,
// otherwise return 0.

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

size_t ProcessMetrics::GetPagefileUsage() const {
  task_basic_info_64 task_info_data;
  if (!GetTaskInfo(TaskForPid(process_), &task_info_data))
    return 0;
  return task_info_data.virtual_size;
}

size_t ProcessMetrics::GetPeakPagefileUsage() const {
  return 0;
}

size_t ProcessMetrics::GetWorkingSetSize() const {
  task_basic_info_64 task_info_data;
  if (!GetTaskInfo(TaskForPid(process_), &task_info_data))
    return 0;
  return task_info_data.resident_size;
}

size_t ProcessMetrics::GetPeakWorkingSetSize() const {
  return 0;
}

// This is a rough approximation of the algorithm that libtop uses.
// private_bytes is the size of private resident memory.
// shared_bytes is the size of shared resident memory.
bool ProcessMetrics::GetMemoryBytes(size_t* private_bytes,
                                    size_t* shared_bytes) {
  kern_return_t kr;
  size_t private_pages_count = 0;
  size_t shared_pages_count = 0;

  if (!private_bytes && !shared_bytes)
    return true;

  mach_port_t task = TaskForPid(process_);
  if (task == MACH_PORT_NULL) {
    DLOG(ERROR) << "Invalid process";
    return false;
  }

  cpu_type_t cpu_type;
  if (!GetCPUTypeForProcess(process_, &cpu_type))
    return false;

  // The same region can be referenced multiple times. To avoid double counting
  // we need to keep track of which regions we've already counted.
  base::hash_set<int> seen_objects;

  // We iterate through each VM region in the task's address map. For shared
  // memory we add up all the pages that are marked as shared. Like libtop we
  // try to avoid counting pages that are also referenced by other tasks. Since
  // we don't have access to the VM regions of other tasks the only hint we have
  // is if the address is in the shared region area.
  //
  // Private memory is much simpler. We simply count the pages that are marked
  // as private or copy on write (COW).
  //
  // See libtop_update_vm_regions in
  // http://www.opensource.apple.com/source/top/top-67/libtop.c
  mach_vm_size_t size = 0;
  for (mach_vm_address_t address = MACH_VM_MIN_ADDRESS;; address += size) {
    vm_region_top_info_data_t info;
    mach_msg_type_number_t info_count = VM_REGION_TOP_INFO_COUNT;
    mach_port_t object_name;
    kr = mach_vm_region(task,
                        &address,
                        &size,
                        VM_REGION_TOP_INFO,
                        (vm_region_info_t)&info,
                        &info_count,
                        &object_name);
    if (kr == KERN_INVALID_ADDRESS) {
      // We're at the end of the address space.
      break;
    } else if (kr != KERN_SUCCESS) {
      DLOG(ERROR) << "Calling mach_vm_region failed with error: "
                 << mach_error_string(kr);
      return false;
    }

    if (IsAddressInSharedRegion(address, cpu_type) &&
        info.share_mode != SM_PRIVATE)
      continue;

    if (info.share_mode == SM_COW && info.ref_count == 1)
      info.share_mode = SM_PRIVATE;

    switch (info.share_mode) {
      case SM_PRIVATE:
        private_pages_count += info.private_pages_resident;
        private_pages_count += info.shared_pages_resident;
        break;
      case SM_COW:
        private_pages_count += info.private_pages_resident;
        // Fall through
      case SM_SHARED:
        if (seen_objects.count(info.obj_id) == 0) {
          // Only count the first reference to this region.
          seen_objects.insert(info.obj_id);
          shared_pages_count += info.shared_pages_resident;
        }
        break;
      default:
        break;
    }
  }

  vm_size_t page_size;
  kr = host_page_size(task, &page_size);
  if (kr != KERN_SUCCESS) {
    DLOG(ERROR) << "Failed to fetch host page size, error: "
               << mach_error_string(kr);
    return false;
  }

  if (private_bytes)
    *private_bytes = private_pages_count * page_size;
  if (shared_bytes)
    *shared_bytes = shared_pages_count * page_size;

  return true;
}

void ProcessMetrics::GetCommittedKBytes(CommittedKBytes* usage) const {
}

bool ProcessMetrics::GetWorkingSetKBytes(WorkingSetKBytes* ws_usage) const {
  size_t priv = GetWorkingSetSize();
  if (!priv)
    return false;
  ws_usage->priv = priv / 1024;
  ws_usage->shareable = 0;
  ws_usage->shared = 0;
  return true;
}

#define TIME_VALUE_TO_TIMEVAL(a, r) do {  \
  (r)->tv_sec = (a)->seconds;             \
  (r)->tv_usec = (a)->microseconds;       \
} while (0)

double ProcessMetrics::GetCPUUsage() {
  mach_port_t task = TaskForPid(process_);
  if (task == MACH_PORT_NULL)
    return 0;

  kern_return_t kr;

  // Libtop explicitly loops over the threads (libtop_pinfo_update_cpu_usage()
  // in libtop.c), but this is more concise and gives the same results:
  task_thread_times_info thread_info_data;
  mach_msg_type_number_t thread_info_count = TASK_THREAD_TIMES_INFO_COUNT;
  kr = task_info(task,
                 TASK_THREAD_TIMES_INFO,
                 reinterpret_cast<task_info_t>(&thread_info_data),
                 &thread_info_count);
  if (kr != KERN_SUCCESS) {
    // Most likely cause: |task| is a zombie.
    return 0;
  }

  task_basic_info_64 task_info_data;
  if (!GetTaskInfo(task, &task_info_data))
    return 0;

  /* Set total_time. */
  // thread info contains live time...
  struct timeval user_timeval, system_timeval, task_timeval;
  TIME_VALUE_TO_TIMEVAL(&thread_info_data.user_time, &user_timeval);
  TIME_VALUE_TO_TIMEVAL(&thread_info_data.system_time, &system_timeval);
  timeradd(&user_timeval, &system_timeval, &task_timeval);

  // ... task info contains terminated time.
  TIME_VALUE_TO_TIMEVAL(&task_info_data.user_time, &user_timeval);
  TIME_VALUE_TO_TIMEVAL(&task_info_data.system_time, &system_timeval);
  timeradd(&user_timeval, &task_timeval, &task_timeval);
  timeradd(&system_timeval, &task_timeval, &task_timeval);

  struct timeval now;
  int retval = gettimeofday(&now, NULL);
  if (retval)
    return 0;

  int64 time = TimeValToMicroseconds(now);
  int64 task_time = TimeValToMicroseconds(task_timeval);

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

  int64 system_time_delta = task_time - last_system_time_;
  int64 time_delta = time - last_time_;
  DCHECK_NE(0U, time_delta);
  if (time_delta == 0)
    return 0;

  last_system_time_ = task_time;
  last_time_ = time;

  return static_cast<double>(system_time_delta * 100.0) / time_delta;
}

bool ProcessMetrics::GetIOCounters(IoCounters* io_counters) const {
  return false;
}

ProcessMetrics::ProcessMetrics(ProcessHandle process,
                               ProcessMetrics::PortProvider* port_provider)
    : process_(process),
      last_time_(0),
      last_system_time_(0),
      port_provider_(port_provider) {
  processor_count_ = SysInfo::NumberOfProcessors();
}

mach_port_t ProcessMetrics::TaskForPid(ProcessHandle process) const {
  mach_port_t task = MACH_PORT_NULL;
  if (port_provider_)
    task = port_provider_->TaskForPid(process_);
  if (task == MACH_PORT_NULL && process_ == getpid())
    task = mach_task_self();
  return task;
}

// Bytes committed by the system.
size_t GetSystemCommitCharge() {
  base::mac::ScopedMachPort host(mach_host_self());
  mach_msg_type_number_t count = HOST_VM_INFO_COUNT;
  vm_statistics_data_t data;
  kern_return_t kr = host_statistics(host, HOST_VM_INFO,
                                     reinterpret_cast<host_info_t>(&data),
                                     &count);
  if (kr) {
    DLOG(WARNING) << "Failed to fetch host statistics.";
    return 0;
  }

  vm_size_t page_size;
  kr = host_page_size(host, &page_size);
  if (kr) {
    DLOG(ERROR) << "Failed to fetch host page size.";
    return 0;
  }

  return (data.active_count * page_size) / 1024;
}

}  // namespace base