// 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 <windows.h>
#include <psapi.h>
#include <stddef.h>
#include <stdint.h>
#include <winternl.h>

#include <algorithm>

#include "base/logging.h"
#include "base/memory/ptr_util.h"
#include "base/process/memory.h"
#include "base/sys_info.h"

#if defined(OS_WIN)
#include <windows.h>
#endif

namespace base {
namespace {

// System pagesize. This value remains constant on x86/64 architectures.
const int PAGESIZE_KB = 4;

typedef NTSTATUS(WINAPI* NTQUERYSYSTEMINFORMATION)(
    SYSTEM_INFORMATION_CLASS SystemInformationClass,
    PVOID SystemInformation,
    ULONG SystemInformationLength,
    PULONG ReturnLength);

}  // namespace

ProcessMetrics::~ProcessMetrics() { }

size_t GetMaxFds() {
  // Windows is only limited by the amount of physical memory.
  return std::numeric_limits<size_t>::max();
}

// static
std::unique_ptr<ProcessMetrics> ProcessMetrics::CreateProcessMetrics(
    ProcessHandle process) {
  return WrapUnique(new ProcessMetrics(process));
}

size_t ProcessMetrics::GetPagefileUsage() const {
  PROCESS_MEMORY_COUNTERS pmc;
  if (GetProcessMemoryInfo(process_.Get(), &pmc, sizeof(pmc))) {
    return pmc.PagefileUsage;
  }
  return 0;
}

// Returns the peak space allocated for the pagefile, in bytes.
size_t ProcessMetrics::GetPeakPagefileUsage() const {
  PROCESS_MEMORY_COUNTERS pmc;
  if (GetProcessMemoryInfo(process_.Get(), &pmc, sizeof(pmc))) {
    return pmc.PeakPagefileUsage;
  }
  return 0;
}

// Returns the current working set size, in bytes.
size_t ProcessMetrics::GetWorkingSetSize() const {
  PROCESS_MEMORY_COUNTERS pmc;
  if (GetProcessMemoryInfo(process_.Get(), &pmc, sizeof(pmc))) {
    return pmc.WorkingSetSize;
  }
  return 0;
}

// Returns the peak working set size, in bytes.
size_t ProcessMetrics::GetPeakWorkingSetSize() const {
  PROCESS_MEMORY_COUNTERS pmc;
  if (GetProcessMemoryInfo(process_.Get(), &pmc, sizeof(pmc))) {
    return pmc.PeakWorkingSetSize;
  }
  return 0;
}

bool ProcessMetrics::GetMemoryBytes(size_t* private_bytes,
                                    size_t* shared_bytes) const {
  // PROCESS_MEMORY_COUNTERS_EX is not supported until XP SP2.
  // GetProcessMemoryInfo() will simply fail on prior OS. So the requested
  // information is simply not available. Hence, we will return 0 on unsupported
  // OSes. Unlike most Win32 API, we don't need to initialize the "cb" member.
  PROCESS_MEMORY_COUNTERS_EX pmcx;
  if (private_bytes &&
      GetProcessMemoryInfo(process_.Get(),
                           reinterpret_cast<PROCESS_MEMORY_COUNTERS*>(&pmcx),
                           sizeof(pmcx))) {
    *private_bytes = pmcx.PrivateUsage;
  }

  if (shared_bytes) {
    WorkingSetKBytes ws_usage;
    if (!GetWorkingSetKBytes(&ws_usage))
      return false;

    *shared_bytes = ws_usage.shared * 1024;
  }

  return true;
}

void ProcessMetrics::GetCommittedKBytes(CommittedKBytes* usage) const {
  MEMORY_BASIC_INFORMATION mbi = {0};
  size_t committed_private = 0;
  size_t committed_mapped = 0;
  size_t committed_image = 0;
  void* base_address = NULL;
  while (VirtualQueryEx(process_.Get(), base_address, &mbi, sizeof(mbi)) ==
         sizeof(mbi)) {
    if (mbi.State == MEM_COMMIT) {
      if (mbi.Type == MEM_PRIVATE) {
        committed_private += mbi.RegionSize;
      } else if (mbi.Type == MEM_MAPPED) {
        committed_mapped += mbi.RegionSize;
      } else if (mbi.Type == MEM_IMAGE) {
        committed_image += mbi.RegionSize;
      } else {
        NOTREACHED();
      }
    }
    void* new_base = (static_cast<BYTE*>(mbi.BaseAddress)) + mbi.RegionSize;
    // Avoid infinite loop by weird MEMORY_BASIC_INFORMATION.
    // If we query 64bit processes in a 32bit process, VirtualQueryEx()
    // returns such data.
    if (new_base <= base_address) {
      usage->image = 0;
      usage->mapped = 0;
      usage->priv = 0;
      return;
    }
    base_address = new_base;
  }
  usage->image = committed_image / 1024;
  usage->mapped = committed_mapped / 1024;
  usage->priv = committed_private / 1024;
}

namespace {

class WorkingSetInformationBuffer {
 public:
  WorkingSetInformationBuffer() {}
  ~WorkingSetInformationBuffer() { Clear(); }

  bool Reserve(size_t size) {
    Clear();
    // Use UncheckedMalloc here because this can be called from the code
    // that handles low memory condition.
    return UncheckedMalloc(size, reinterpret_cast<void**>(&buffer_));
  }

  const PSAPI_WORKING_SET_INFORMATION* operator ->() const { return buffer_; }

  size_t GetPageEntryCount() const { return number_of_entries; }

  // This function is used to get page entries for a process.
  bool QueryPageEntries(const ProcessHandle& process) {
    int retries = 5;
    number_of_entries = 4096;  // Just a guess.

    for (;;) {
      size_t buffer_size =
          sizeof(PSAPI_WORKING_SET_INFORMATION) +
          (number_of_entries * sizeof(PSAPI_WORKING_SET_BLOCK));

      if (!Reserve(buffer_size))
        return false;

      // On success, |buffer_| is populated with info about the working set of
      // |process|. On ERROR_BAD_LENGTH failure, increase the size of the
      // buffer and try again.
      if (QueryWorkingSet(process, buffer_, buffer_size))
        break;  // Success

      if (GetLastError() != ERROR_BAD_LENGTH)
        return false;

      number_of_entries = buffer_->NumberOfEntries;

      // Maybe some entries are being added right now. Increase the buffer to
      // take that into account. Increasing by 10% should generally be enough,
      // especially considering the potentially low memory condition during the
      // call (when called from OomMemoryDetails) and the potentially high
      // number of entries (300K was observed in crash dumps).
      number_of_entries *= 1.1;

      if (--retries == 0) {
        // If we're looping, eventually fail.
        return false;
      }
    }

    // TODO(chengx): Remove the comment and the logic below. It is no longer
    // needed since we don't have Win2000 support.
    // On windows 2000 the function returns 1 even when the buffer is too small.
    // The number of entries that we are going to parse is the minimum between
    // the size we allocated and the real number of entries.
    number_of_entries = std::min(number_of_entries,
                                 static_cast<size_t>(buffer_->NumberOfEntries));

    return true;
  }

 private:
  void Clear() {
    free(buffer_);
    buffer_ = nullptr;
  }

  PSAPI_WORKING_SET_INFORMATION* buffer_ = nullptr;

  // Number of page entries.
  size_t number_of_entries = 0;

  DISALLOW_COPY_AND_ASSIGN(WorkingSetInformationBuffer);
};

}  // namespace

bool ProcessMetrics::GetWorkingSetKBytes(WorkingSetKBytes* ws_usage) const {
  size_t ws_private = 0;
  size_t ws_shareable = 0;
  size_t ws_shared = 0;

  DCHECK(ws_usage);
  memset(ws_usage, 0, sizeof(*ws_usage));

  WorkingSetInformationBuffer buffer;
  if (!buffer.QueryPageEntries(process_.Get()))
    return false;

  size_t num_page_entries = buffer.GetPageEntryCount();
  for (size_t i = 0; i < num_page_entries; i++) {
    if (buffer->WorkingSetInfo[i].Shared) {
      ws_shareable++;
      if (buffer->WorkingSetInfo[i].ShareCount > 1)
        ws_shared++;
    } else {
      ws_private++;
    }
  }

  ws_usage->priv = ws_private * PAGESIZE_KB;
  ws_usage->shareable = ws_shareable * PAGESIZE_KB;
  ws_usage->shared = ws_shared * PAGESIZE_KB;

  return true;
}

// This function calculates the proportional set size for a process.
bool ProcessMetrics::GetProportionalSetSizeBytes(uint64_t* pss_bytes) const {
  double ws_pss = 0.0;

  WorkingSetInformationBuffer buffer;
  if (!buffer.QueryPageEntries(process_.Get()))
    return false;

  size_t num_page_entries = buffer.GetPageEntryCount();
  for (size_t i = 0; i < num_page_entries; i++) {
    if (buffer->WorkingSetInfo[i].Shared &&
        buffer->WorkingSetInfo[i].ShareCount > 0)
      ws_pss += 1.0 / buffer->WorkingSetInfo[i].ShareCount;
    else
      ws_pss += 1.0;
  }

  *pss_bytes = static_cast<uint64_t>(ws_pss * GetPageSize());
  return true;
}

static uint64_t FileTimeToUTC(const FILETIME& ftime) {
  LARGE_INTEGER li;
  li.LowPart = ftime.dwLowDateTime;
  li.HighPart = ftime.dwHighDateTime;
  return li.QuadPart;
}

double ProcessMetrics::GetPlatformIndependentCPUUsage() {
  FILETIME creation_time;
  FILETIME exit_time;
  FILETIME kernel_time;
  FILETIME user_time;

  if (!GetProcessTimes(process_.Get(), &creation_time, &exit_time, &kernel_time,
                       &user_time)) {
    // We don't assert here because in some cases (such as in the Task Manager)
    // we may call this function on a process that has just exited but we have
    // not yet received the notification.
    return 0;
  }
  int64_t system_time = FileTimeToUTC(kernel_time) + FileTimeToUTC(user_time);
  TimeTicks time = TimeTicks::Now();

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

  int64_t system_time_delta = system_time - last_system_time_;
  // FILETIME is in 100-nanosecond units, so this needs microseconds times 10.
  int64_t time_delta = (time - last_cpu_time_).InMicroseconds() * 10;
  DCHECK_NE(0U, time_delta);
  if (time_delta == 0)
    return 0;


  last_system_time_ = system_time;
  last_cpu_time_ = time;

  return static_cast<double>(system_time_delta * 100) / time_delta;
}

bool ProcessMetrics::GetIOCounters(IoCounters* io_counters) const {
  return GetProcessIoCounters(process_.Get(), io_counters) != FALSE;
}

ProcessMetrics::ProcessMetrics(ProcessHandle process) : last_system_time_(0) {
  if (process) {
    HANDLE duplicate_handle;
    BOOL result = ::DuplicateHandle(::GetCurrentProcess(), process,
                                    ::GetCurrentProcess(), &duplicate_handle,
                                    PROCESS_QUERY_INFORMATION, FALSE, 0);
    DCHECK(result);
    process_.Set(duplicate_handle);
  }
}

size_t GetSystemCommitCharge() {
  // Get the System Page Size.
  SYSTEM_INFO system_info;
  GetSystemInfo(&system_info);

  PERFORMANCE_INFORMATION info;
  if (!GetPerformanceInfo(&info, sizeof(info))) {
    DLOG(ERROR) << "Failed to fetch internal performance info.";
    return 0;
  }
  return (info.CommitTotal * system_info.dwPageSize) / 1024;
}

size_t GetPageSize() {
  return PAGESIZE_KB * 1024;
}

// This function uses the following mapping between MEMORYSTATUSEX and
// SystemMemoryInfoKB:
//   ullTotalPhys ==> total
//   ullAvailPhys ==> avail_phys
//   ullTotalPageFile ==> swap_total
//   ullAvailPageFile ==> swap_free
bool GetSystemMemoryInfo(SystemMemoryInfoKB* meminfo) {
  MEMORYSTATUSEX mem_status;
  mem_status.dwLength = sizeof(mem_status);
  if (!::GlobalMemoryStatusEx(&mem_status))
    return false;

  meminfo->total = mem_status.ullTotalPhys / 1024;
  meminfo->avail_phys = mem_status.ullAvailPhys / 1024;
  meminfo->swap_total = mem_status.ullTotalPageFile / 1024;
  meminfo->swap_free = mem_status.ullAvailPageFile / 1024;

  return true;
}

size_t ProcessMetrics::GetMallocUsage() {
  // Unsupported as getting malloc usage on Windows requires iterating through
  // the heap which is slow and crashes.
  return 0;
}

}  // namespace base