Make task manager memory data more efficient and meaningful.

base/process/private_working_set_snapshot.h

+// Copyright (c) 2009 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.
+
+#ifndef PRIVATE_WORKING_SET_SNAPSHOT_H_
+#define PRIVATE_WORKING_SET_SNAPSHOT_H_
+
+#include <vector>
+
+#include "base/base_export.h"
+#include "base/process/process_handle.h"
+#include "base/win/scoped_handle.h"
+
+#if defined(OS_WIN)
+
+#include <pdh.h>
+
+namespace base {
+
+namespace win {
+
+// The traits class for PDH handles that can be closed via PdhCloseQuery() API.
+class PDHHandleTraits {
+ public:
+  typedef PDH_HQUERY Handle;
+
+  // Closes the handle.
+  static bool BASE_EXPORT CloseHandle(PDH_HQUERY handle) {
+    return (PdhCloseQuery(handle) == ERROR_SUCCESS);
+  }
+
+  // Returns true if the handle value is valid.
+  static bool IsHandleValid(PDH_HQUERY handle) {
+    return handle != nullptr;
+  }
+
+  // Returns NULL handle value.
+  static PDH_HQUERY NullHandle() {
+    return nullptr;
+  }
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(PDHHandleTraits);
+};
+
+
+// Do-nothing verifier.
+class PDHDummyVerifierTraits {

[ncarter (slow), 2015/06/26 21:50:46]

Does using the preexisting DummyVerifier not compile? I thought that PDH_HQUERY
was just ultimately a typedef for HANDLE.

[brucedawson, 2015/06/27 00:13:06]

You're right, it is. I also followed the pattern you linked to and got a much
more concise PDHHandleTraits. The line-count overhead seems much more reasonable
now.

+ public:
+  typedef PDH_HQUERY Handle;
+
+  static void StartTracking(PDH_HQUERY handle, const void* owner,
+                            const void* pc1, const void* pc2) {}
+  static void StopTracking(PDH_HQUERY handle, const void* owner,
+                           const void* pc1, const void* pc2) {}
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(PDHDummyVerifierTraits);
+};
+
+typedef GenericScopedHandle<PDHHandleTraits, PDHDummyVerifierTraits> 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 BASE_EXPORT PrivateWorkingSetSnapshot {
+ public:
+  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.
+  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;
+
+ private:
+  // The handle to the query object.
+  win::ScopedPDH query_handle_;
+
+  // 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 {
+    // 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;
+  };
+  std::vector<PdhCounterPair> counter_pairs_;
+
+  struct PidAndPrivateWS {
+    base::ProcessId process_id;
+    size_t private_ws;
+    // Comparison function for sorting.
+    bool operator<(const PidAndPrivateWS& other) const {
+      return process_id < other.process_id;
+    }
+    // Comparison function for searching.
+    bool operator<(const base::ProcessId other_process_id) const {
+      return process_id < other_process_id;
+    }
+  };
+  // After each call to Sample this will hold the results, sorted by process id.
+  std::vector<PidAndPrivateWS> records_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrivateWorkingSetSnapshot);
+};
+
+}  // namespace base
+
+#endif  // defined(OS_WIN)
+
+#endif  // PRIVATE_WORKING_SET_SNAPSHOT_H_