Task manager: Get physical memory efficiently for all processes from SharedSampler

chrome/browser/win/private_working_set_snapshot_unittest.cc

-// 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 "chrome/browser/win/private_working_set_snapshot.h"
-
-#include <stddef.h>
-
-#include "base/win/windows_version.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-using PrivateWorkingSetSnapshotWinTest = testing::Test;
-
-TEST_F(PrivateWorkingSetSnapshotWinTest, FindPidSelfTest) {
-  // The Pdh APIs are supported on Windows XP and above, but the "Working Set -
-  // Private" counter that PrivateWorkingSetSnapshot depends on is not defined
-  // until Windows Vista and is not reliable until Windows 7. Early-out to avoid
-  // test failure.
-  if (base::win::GetVersion() <= base::win::VERSION_VISTA)
-    return;
-
-  // Sample this process.
-  base::ProcessId pid = base::GetCurrentProcId();
-
-  PrivateWorkingSetSnapshot private_ws_snapshot;
-
-  private_ws_snapshot.AddToMonitorList("unit_tests");
-  private_ws_snapshot.Sample();
-
-  size_t private_ws = private_ws_snapshot.GetPrivateWorkingSet(pid);
-  if (private_ws == 0) {
-    // The Pdh APIs which PrivateWorkingSetSnapshot depends on are flaky and
-    // sometimes (~5% of the time on win_chromium_rel_ng) give back a result of
-    // zero. This is handled seamlessly in task manager by falling back to the
-    // old calculations so it is not a critical failure. Checking for this case
-    // and skipping the test stops flaky-test failures.
-    return;
-  }
-
-  // Private working set is difficult to predict but should be at least several
-  // MB. Initial tests show a value of 19+ MB depending on how many tests and
-  // processes are used. Anomalously small or large values would warrant
-  // investigation.
-  EXPECT_GT(private_ws, 2000000u);
-  // Check that the WS is less than 1500 MB. This is set very high to reduce the
-  // chance that unrelated changes could ever make this fail. This mostly just
-  // checks against some uncaught error that might return 0xFFFFFFFF. When run
-  // under Dr Memory the private working set was seen to be about 850 MB, which
-  // is why such a high threshold has been chosen.
-  EXPECT_LT(private_ws, 1500000000u);
-
-  // Allocate and touch a large block of memory (vector's constructor will zero
-  // every entry). This will increase the private working set.
-  const size_t alloc_size = 10000000;
-  std::vector<char> big_memory(alloc_size);
-
-  size_t private_ws2 = private_ws_snapshot.GetPrivateWorkingSet(pid);
-  EXPECT_EQ(private_ws, private_ws2) << "GetPrivateWorkingSet should be "
-                                        "consistent until the next call to "
-                                        "Sample()";
-
-  private_ws_snapshot.Sample();
-  size_t private_ws3 = private_ws_snapshot.GetPrivateWorkingSet(pid);
-  EXPECT_GT(private_ws3, private_ws2 + alloc_size / 2)
-      << "GetPrivateWorkingSet should increase as we allocate more memory";
-}