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// Copyright 2015 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 "build/build_config.h"
#if defined(OS_WIN)
#include <pdh.h>
#include <vector>
#include "base/process/process_handle.h"
#include "base/win/scoped_handle.h"
namespace win {
// The traits class for PDH handles that can be closed via PdhCloseQuery() API.
struct PDHHandleTraits {
typedef PDH_HQUERY Handle;
static PDH_HQUERY NullHandle() { return nullptr; }
static bool IsHandleValid(PDH_HQUERY handle) { return handle != nullptr; }
static bool CloseHandle(PDH_HQUERY handle) {
return (PdhCloseQuery(handle) == ERROR_SUCCESS);
// DummyVerifierTraits can be used because PDH_HQUERY is just a typedef for
// HANDLE. However HandleTraits cannot be used because PdhCloseQuery must be
// called rather than CloseHandle to dispose of the resources.
using ScopedPDH =
} // namespace win
// This class can be used to do bulk collection of private working sets. This
// exists because on Windows it is much faster to collect a group of private
// working sets all at once using PdhOpenQuery than to calculate the private
// working sets for each process individually.
class PrivateWorkingSetSnapshot {
// Add a process name that this object should monitor, such as "chrome". All
// processes whose name starts with this string will be monitored.
void AddToMonitorList(const std::string& process_name);
// Query the system for working-set information for all monitored processes
// and update the results cache. This function may take a few ms to run.
// The time it takes seems to be independent of the number of processes it
// retrieves data for. This makes it faster than using QueryWorkingSet as soon
// as the process count exceeds two or three.
void Sample();
// Ask for the working set for a specific process, from the most recent call
// to Sample. If no data is available then zero will be returned. The result
// is in bytes.
size_t GetPrivateWorkingSet(base::ProcessId process_id) const;
// Initialize the PDH |query_handle_| and process any pending AddToMonitorList
// calls.
void Initialize();
// This holds a pair of Pdh counters to queries for the process ID and private
// working set for a particular process name being monitored. The results from
// the two queries can be matched up so that we can associate a private
// working set with a process ID.
struct PdhCounterPair {
// These are bound to query_handle_ and will be freed when it is closed.
// The handle to the 'counter' that retrieves process IDs.
PDH_HCOUNTER process_id_handle = nullptr;
// The handle to the 'counter' that retrieves private working sets.
PDH_HCOUNTER private_ws_handle = nullptr;
// Struct for storing a process ID and associated private working set.
struct PidAndPrivateWorkingSet {
base::ProcessId process_id;
size_t private_ws;
// Comparison function for sorting by process ID.
bool operator<(const PidAndPrivateWorkingSet& other) const {
// private_ws is intentionally *not* part of the comparison because it is
// the payload and process_id is the key.
return process_id < other.process_id;
// Comparison function for searching by process ID.
bool operator<(const base::ProcessId other_process_id) const {
return process_id < other_process_id;
// True if Initialize() has been called, whether it succeeded or not.
bool initialized_ = false;
// The handle to the query object.
win::ScopedPDH query_handle_;
// A vector of process names to monitor when initialization occurs.
std::vector<std::string> process_names_;
// A PdhCounterPair for each successful AddToMonitorList call.
std::vector<PdhCounterPair> counter_pairs_;
// After each call to Sample this will hold the results, sorted by process id.
std::vector<PidAndPrivateWorkingSet> records_;
#endif // defined(OS_WIN)