Add method for suppressing MemoryPressureListener notifications
This patch adds a new static method to MemoryPressureListener which can
be used to start/stop suppressing memory pressure notifications:
// Start suppressing memory pressure notifications.
MemoryPressureListener::SetNotificationsSuppressed(true);
// Stop suppressing memory pressure notifications.
MemoryPressureListener::SetNotificationsSuppressed(false);
This patch represents the first step towards implementing a DevTools API
for suppressing and simulating memory pressure signals in Chrome. The
main use case for this feature is to enforce consistent conditions
across memory measurements. See https://goo.gl/cZFdH3 for more details.
BUG=516776
Review URL: https://codereview.chromium.org/1312163003
Cr-Commit-Position: refs/heads/master@{#347622}
CrOS-Libchrome-Original-Commit: da4982addfa8b6a5e25b794565c6c7158c1ec8cc
diff --git a/base/memory/memory_pressure_listener.cc b/base/memory/memory_pressure_listener.cc
index 2a1be74..8071d37 100644
--- a/base/memory/memory_pressure_listener.cc
+++ b/base/memory/memory_pressure_listener.cc
@@ -32,6 +32,10 @@
ObserverListThreadSafe<MemoryPressureListener>,
LeakyLazyObserverListTraits> g_observers = LAZY_INSTANCE_INITIALIZER;
+// All memory pressure notifications within this process will be suppressed if
+// this variable is set to 1.
+subtle::Atomic32 g_notifications_suppressed = 0;
+
} // namespace
MemoryPressureListener::MemoryPressureListener(
@@ -54,8 +58,20 @@
DCHECK_NE(memory_pressure_level, MEMORY_PRESSURE_LEVEL_NONE);
TRACE_EVENT1("memory", "MemoryPressureListener::NotifyMemoryPressure",
"level", memory_pressure_level);
+ if (AreNotificationsSuppressed())
+ return;
g_observers.Get().Notify(FROM_HERE, &MemoryPressureListener::Notify,
memory_pressure_level);
}
+// static
+bool MemoryPressureListener::AreNotificationsSuppressed() {
+ return subtle::Acquire_Load(&g_notifications_suppressed) == 1;
+}
+
+// static
+void MemoryPressureListener::SetNotificationsSuppressed(bool suppress) {
+ subtle::Release_Store(&g_notifications_suppressed, suppress ? 1 : 0);
+}
+
} // namespace base
diff --git a/base/memory/memory_pressure_listener.h b/base/memory/memory_pressure_listener.h
index 6adaeee..83d47d7 100644
--- a/base/memory/memory_pressure_listener.h
+++ b/base/memory/memory_pressure_listener.h
@@ -72,6 +72,12 @@
// Intended for use by the platform specific implementation.
static void NotifyMemoryPressure(MemoryPressureLevel memory_pressure_level);
+ // These methods should not be used anywhere else but in memory measurement
+ // code, where they are intended to maintain stable conditions across
+ // measurements.
+ static bool AreNotificationsSuppressed();
+ static void SetNotificationsSuppressed(bool suppressed);
+
private:
void Notify(MemoryPressureLevel memory_pressure_level);
diff --git a/base/memory/memory_pressure_listener_unittest.cc b/base/memory/memory_pressure_listener_unittest.cc
new file mode 100644
index 0000000..1bcab2f
--- /dev/null
+++ b/base/memory/memory_pressure_listener_unittest.cc
@@ -0,0 +1,52 @@
+// 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/memory/memory_pressure_listener.h"
+
+#include "base/bind.h"
+#include "base/message_loop/message_loop.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+namespace base {
+
+using MockCallback =
+ testing::MockFunction<void(MemoryPressureListener::MemoryPressureLevel)>;
+
+TEST(MemoryPressureListenerTest, NotifyMemoryPressure) {
+ MessageLoopForUI message_loop;
+ MockCallback callback;
+ scoped_ptr<MemoryPressureListener> listener(new MemoryPressureListener(
+ Bind(&MockCallback::Call, Unretained(&callback))));
+
+ // Memory pressure notifications are not suppressed by default.
+ EXPECT_FALSE(MemoryPressureListener::AreNotificationsSuppressed());
+ EXPECT_CALL(callback,
+ Call(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE))
+ .Times(1);
+ MemoryPressureListener::NotifyMemoryPressure(
+ MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE);
+ message_loop.RunUntilIdle();
+
+ // Enable suppressing memory pressure notifications.
+ MemoryPressureListener::SetNotificationsSuppressed(true);
+ EXPECT_TRUE(MemoryPressureListener::AreNotificationsSuppressed());
+ EXPECT_CALL(callback, Call(testing::_)).Times(0);
+ MemoryPressureListener::NotifyMemoryPressure(
+ MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE);
+ message_loop.RunUntilIdle();
+
+ // Disable suppressing memory pressure notifications.
+ MemoryPressureListener::SetNotificationsSuppressed(false);
+ EXPECT_FALSE(MemoryPressureListener::AreNotificationsSuppressed());
+ EXPECT_CALL(callback,
+ Call(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL))
+ .Times(1);
+ MemoryPressureListener::NotifyMemoryPressure(
+ MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL);
+ message_loop.RunUntilIdle();
+
+ listener.reset();
+}
+
+} // namespace base