React immediately to memory pressure on foreground threads

test/unittests/api/isolate-unittest.cc

+// Copyright 2017 the V8 project 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 "testing/gtest/include/gtest/gtest.h"
+
+#include "include/libplatform/libplatform.h"
+#include "include/v8-platform.h"
+#include "include/v8.h"
+#include "src/base/macros.h"
+#include "src/base/platform/semaphore.h"
+#include "src/execution.h"
+#include "src/isolate.h"
+#include "src/v8.h"
+#include "test/unittests/test-utils.h"
+
+namespace v8 {
+
+typedef TestWithIsolate IsolateTest;
+
+namespace {
+
+class MemoryPressureTask : public v8::Task {
+ public:
+  MemoryPressureTask(Isolate* isolate, base::Semaphore* semaphore)
+      : isolate_(isolate), semaphore_(semaphore) {}
+  ~MemoryPressureTask() override = default;
+
+  // v8::Task implementation.
+  void Run() override {
+    isolate_->MemoryPressureNotification(MemoryPressureLevel::kCritical);
+    semaphore_->Signal();
+  }
+
+ private:
+  Isolate* isolate_;
+  base::Semaphore* semaphore_;
+
+  DISALLOW_COPY_AND_ASSIGN(MemoryPressureTask);
+};
+
+}  // namespace
+
+// Check that triggering a memory pressure notification on the isolate thread
+// doesn't request a GC interrupt.
+TEST_F(IsolateTest, MemoryPressureNotificationForeground) {
+  Isolate::Scope isolate_scope(isolate());
+
+  internal::Isolate* i_isolate =
+      reinterpret_cast<internal::Isolate*>(isolate());
+
+  ASSERT_FALSE(i_isolate->stack_guard()->CheckGC());
+  isolate()->MemoryPressureNotification(MemoryPressureLevel::kCritical);
+  ASSERT_FALSE(i_isolate->stack_guard()->CheckGC());
+}
+
+// Check that triggering a memory pressure notification on an background thread
+// requests a GC interrupt.
+TEST_F(IsolateTest, MemoryPressureNotificationBackground) {
+  Isolate::Scope isolate_scope(isolate());
+
+  internal::Isolate* i_isolate =
+      reinterpret_cast<internal::Isolate*>(isolate());
+
+  base::Semaphore semaphore(0);
+
+  internal::V8::GetCurrentPlatform()->CallOnBackgroundThread(
+      new MemoryPressureTask(isolate(), &semaphore),
+      v8::Platform::kShortRunningTask);
+
+  semaphore.Wait();
+
+  ASSERT_TRUE(i_isolate->stack_guard()->CheckGC());
+  v8::platform::PumpMessageLoop(internal::V8::GetCurrentPlatform(), isolate());
+}
+
+}  // namespace v8