Create base::win::MemoryPressureMonitor class.

base/win/memory_pressure_monitor_win_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 "base/basictypes.h"
+#include "base/memory/memory_pressure_listener.h"
+#include "base/message_loop/message_loop.h"
+#include "base/win/memory_pressure_monitor_win.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+namespace {
+
+// True if the memory notifier got called.

[grt (UTC plus 2), 2015/05/05 15:34:00]

you could use Google Mock here rather than rolling your own. let me know if
you'd like suggestions on how to do so.

[chrisha, 2015/05/05 19:46:13]

Yeah, I use gmock all over the place in Syzygy land, but I thought gmock was
kind of deprecated in Chrome these days?

[grt (UTC plus 2), 2015/05/06 13:26:36]

My personal belief is that gmock is okay to use when it's the right tool for the
job. Some may say "but gmock is hard to understand." To them, I say, "so is each
test's custom and unique fixture code that emulates gmock." It's possible that
another reviewer would disagree with me, so take this as just, like, my opinion,
man.

+// Do not read/modify value directly.
+bool on_memory_pressure_called = false;
+
+// If the memory notifier got called, this is the memory pressure reported.
+MemoryPressureListener::MemoryPressureLevel on_memory_pressure_level =
+    MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE;
+
+// Processes OnMemoryPressure calls.
+void OnMemoryPressure(MemoryPressureListener::MemoryPressureLevel level) {
+  on_memory_pressure_called = true;
+  on_memory_pressure_level = level;
+}
+
+// Resets the indicator for memory pressure.
+void ResetOnMemoryPressureCalled() {
+  on_memory_pressure_called = false;
+}
+
+// Returns true when OnMemoryPressure was called (and resets it).
+bool WasOnMemoryPressureCalled() {
+  bool b = on_memory_pressure_called;
+  ResetOnMemoryPressureCalled();
+  return b;
+}
+
+struct PressureSettings {
+  int phys;
+  int virt;
+  MemoryPressureListener::MemoryPressureLevel level;
+};
+
+}  // namespace
+
+// This is outside of the anonymous namespace so that it can be seen as a friend
+// to the monitor class.
+class TestMemoryPressureMonitor : public MemoryPressureMonitorWin {
+ public:
+  using MemoryPressureMonitorWin::CalculateCurrentPressureLevel;
+  using MemoryPressureMonitorWin::CheckMemoryPressure;
+
+  TestMemoryPressureMonitor() {
+    // Disable any timers which are going on and set a special memory reporting
+    // function.
+    StopObserving();
+  }
+
+  virtual ~TestMemoryPressureMonitor() {}
+
+  // Sets up the memory status to reflect the provided loads.
+  void SetMemoryLoad(int phys_load_pct, int virt_load_pct) {
+    static const DWORDLONG k4GB = 4ull * 1024 * 1024 * 1024;
+
+    mem_status_.dwMemoryLoad = static_cast<DWORD>(phys_load_pct);
+    mem_status_.ullTotalPhys = k4GB;
+    mem_status_.ullAvailPhys = (k4GB * (100 - phys_load_pct)) / 100;
+    mem_status_.ullTotalPageFile = k4GB;
+    mem_status_.ullAvailPageFile = k4GB;
+    mem_status_.ullTotalVirtual = k4GB;
+    mem_status_.ullAvailVirtual = (k4GB * (100 - virt_load_pct)) / 100;
+  }
+
+  // Sets up the memory status to reflect the provided absolute memory left.
+  // This uses quite small total memory quantities so that the absolute memory
+  // limits have a chance to kick in.
+  void SetMemoryFree(int phys_left_mb, int virt_left_mb) {
+    // Figure out an amount of memory that makes sense for the desired
+    // quantities of memory to be left.
+    DWORDLONG total = 64;  // Minimum of 64MB.
+    while (total < phys_left_mb || total < virt_left_mb)
+      total *= 2;
+    total *= 1024 * 1024;
+
+    mem_status_.ullTotalPhys = total;
+    mem_status_.ullAvailPhys =
+        static_cast<DWORDLONG>(phys_left_mb) * 1024 * 1024;
+    mem_status_.ullTotalPageFile = total;
+    mem_status_.ullAvailPageFile = total;
+    mem_status_.ullTotalVirtual = total;
+    mem_status_.ullAvailVirtual =
+        static_cast<DWORDLONG>(virt_left_mb) * 1024 * 1024;
+    mem_status_.dwMemoryLoad = static_cast<DWORD>(
+        100 * (mem_status_.ullTotalPhys - mem_status_.ullAvailPhys) /
+        mem_status_.ullTotalPhys);
+  }
+
+ private:
+  virtual bool GetSystemMemoryStatus(_MEMORYSTATUSEX* mem_status) override {
+    // Simply copy the memory status set by the test fixture.
+    *mem_status = mem_status_;
+    return true;
+  }
+
+  _MEMORYSTATUSEX mem_status_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestMemoryPressureMonitor);
+};
+
+// Tests the fundamental direct calculation of memory pressure.
+TEST(MemoryPressureMonitorWinTest, CalculateCurrentMemoryPressureLevel) {
+  base::MessageLoopForUI message_loop;
+  scoped_ptr<TestMemoryPressureMonitor> monitor(

[grt (UTC plus 2), 2015/05/05 15:34:00]

why not put the instance on the stack?

[chrisha, 2015/05/05 19:46:13]

No real reason, other than cut and paste from MemoryPressureMonitorChromeOS.
Done.

+      new TestMemoryPressureMonitor);
+
+  // A bunch of memory load settings and the expected memory pressure.
+  const PressureSettings kLoadSettings[] = {
+      { 10, 10, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE },
+      { 40, 40, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE },
+      { 65, 10, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE },
+      { 10, 65, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE },
+      { 65, 65, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE },
+      { 98, 10, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL },
+      { 98, 65, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL },
+      { 10, 98, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL },
+      { 65, 98, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL },
+      { 98, 98, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL },
+  };
+
+  for (size_t i = 0; i < arraysize(kLoadSettings); ++i) {

[grt (UTC plus 2), 2015/05/05 15:34:00]

  for (const PressureSettings& setting : kLoadSettings)
here and elsewhere

[chrisha, 2015/05/05 19:46:13]

Done.

+    monitor->SetMemoryLoad(kLoadSettings[i].phys, kLoadSettings[i].virt);
+    EXPECT_EQ(kLoadSettings[i].level,
+              monitor->CalculateCurrentPressureLevel());
+  }
+
+  // A bunch of free memory settings and the expected memory pressure.
+  const PressureSettings kFreeSettings[] = {
+      { 500, 500, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE },
+      { 250, 500, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE },
+      { 500, 250, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE },
+      { 250, 250, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE },
+      { 50, 500, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL },
+      { 50, 250, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL },
+      { 500, 50, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL },
+      { 250, 50, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL },
+      { 50, 50, MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL },
+  };
+
+  for (size_t i = 0; i < arraysize(kFreeSettings); ++i) {
+    monitor->SetMemoryFree(kFreeSettings[i].phys, kFreeSettings[i].virt);
+    EXPECT_EQ(kFreeSettings[i].level,
+              monitor->CalculateCurrentPressureLevel());
+  }
+}
+
+// This test tests the various transition states from memory pressure, looking
+// for the correct behavior on event reposting as well as state updates.
+TEST(MemoryPressureMonitorWinTest, CheckMemoryPressure) {
+  base::MessageLoopForUI message_loop;

[grt (UTC plus 2), 2015/05/05 15:34:00]

does this test use the timer? if so, it'll be a slow test, which is problematic.
if so, see if using TestSimpleTaskRunner rather than MessageLoopForUI will make
the timer's postings into the future fire immediately.

[chrisha, 2015/05/05 19:46:13]

No, the test bypasses the timer entirely by directly calling the
CheckMemoryPressure function (which is what the timer itself calls). It
simulates the timer firing repeatedly in this manner.

+  scoped_ptr<TestMemoryPressureMonitor> monitor(
+      new TestMemoryPressureMonitor);
+  scoped_ptr<MemoryPressureListener> listener(
+      new MemoryPressureListener(base::Bind(&OnMemoryPressure)));
+
+  // Checking the memory pressure while 0% are used should not produce any
+  // events.
+  ResetOnMemoryPressureCalled();
+  monitor->SetMemoryLoad(0, 0);
+  monitor->CheckMemoryPressure();
+  message_loop.RunUntilIdle();
+  EXPECT_FALSE(WasOnMemoryPressureCalled());
+  EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE,
+            monitor->GetCurrentPressureLevel());
+
+  // Setting the memory level to 80% should produce a moderate pressure level.
+  monitor->SetMemoryLoad(80, 80);
+  monitor->CheckMemoryPressure();
+  message_loop.RunUntilIdle();
+  EXPECT_TRUE(WasOnMemoryPressureCalled());
+  EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE,
+            monitor->GetCurrentPressureLevel());
+  EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE,
+            on_memory_pressure_level);
+
+  // We need to check that the event gets reposted after a while.
+  int i = 0;
+  for (; i < 100; i++) {
+    monitor->CheckMemoryPressure();
+    message_loop.RunUntilIdle();
+    EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE,
+              monitor->GetCurrentPressureLevel());
+    if (WasOnMemoryPressureCalled()) {
+      EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE,
+                on_memory_pressure_level);
+      break;
+    }
+  }
+  // Should be more then 5 and less then 100.
+  EXPECT_LE(5, i);
+  EXPECT_GE(99, i);
+
+  // Setting the memory usage to 99% should produce critical levels.
+  monitor->SetMemoryLoad(99, 99);
+  monitor->CheckMemoryPressure();
+  message_loop.RunUntilIdle();
+  EXPECT_TRUE(WasOnMemoryPressureCalled());
+  EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL,
+            on_memory_pressure_level);
+  EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL,
+            monitor->GetCurrentPressureLevel());
+
+  // Calling it again should immediately produce a second call.
+  monitor->CheckMemoryPressure();
+  message_loop.RunUntilIdle();
+  EXPECT_TRUE(WasOnMemoryPressureCalled());
+  EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL,
+            on_memory_pressure_level);
+  EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL,
+            monitor->GetCurrentPressureLevel());
+
+  // When lowering the pressure again we should get an event and the
+  // pressure should go back to moderate.
+  monitor->SetMemoryLoad(80, 80);
+  monitor->CheckMemoryPressure();
+  message_loop.RunUntilIdle();
+  EXPECT_TRUE(WasOnMemoryPressureCalled());
+  EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE,
+            on_memory_pressure_level);
+  EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE,
+            monitor->GetCurrentPressureLevel());
+
+  // We should need exactly the same amount of calls as before, before the next
+  // call comes in.
+  int j = 0;
+  for (; j < 100; j++) {
+    monitor->CheckMemoryPressure();
+    message_loop.RunUntilIdle();
+    EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE,
+              monitor->GetCurrentPressureLevel());
+    if (WasOnMemoryPressureCalled()) {
+      EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE,
+                on_memory_pressure_level);
+      break;
+    }
+  }
+  // We should have needed exactly the same amount of checks as before.
+  EXPECT_EQ(j, i);
+
+  // Going down to no pressure should not produce an event.
+  monitor->SetMemoryLoad(0, 0);
+  monitor->CheckMemoryPressure();
+  message_loop.RunUntilIdle();
+  EXPECT_FALSE(WasOnMemoryPressureCalled());
+  EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE,
+            monitor->GetCurrentPressureLevel());
+}
+
+}  // namespace base