Reland "Throttle resource message requests during user interaction"

content/renderer/scheduler/resource_dispatch_throttler_unittest.cc

+// Copyright 2014 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 "content/renderer/scheduler/resource_dispatch_throttler.h"
+
+#include "base/memory/scoped_vector.h"
+#include "content/common/resource_messages.h"
+#include "content/test/fake_renderer_scheduler.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace content {
+namespace {
+
+const uint32 kRequestsPerFlush = 4;
+const double kFlushPeriodSeconds = 1.f / 60;
+const int kRoutingId = 1;
+
+typedef ScopedVector<IPC::Message> ScopedMessages;
+
+int GetRequestId(const IPC::Message& msg) {
+  int request_id = -1;
+  switch (msg.type()) {
+    case ResourceHostMsg_RequestResource::ID: {
+      PickleIterator iter(msg);
+      int routing_id = -1;
+      if (!iter.ReadInt(&routing_id) || !iter.ReadInt(&request_id))
+        NOTREACHED() << "Invalid id for resource request message.";
+    } break;
+
+    case ResourceHostMsg_DidChangePriority::ID:
+    case ResourceHostMsg_ReleaseDownloadedFile::ID:
+    case ResourceHostMsg_CancelRequest::ID:
+      if (!PickleIterator(msg).ReadInt(&request_id))
+        NOTREACHED() << "Invalid id for resource message.";
+      break;
+
+    default:
+      NOTREACHED() << "Invalid message for resource throttling.";
+      break;
+  }
+  return request_id;
+}
+
+class SenderSink : public IPC::Sender {
+ public:
+  SenderSink(ScopedMessages* sent_messages) : sent_messages_(sent_messages) {}
+
+  // IPC::Sender implementation:
+  bool Send(IPC::Message* msg) override {
+    sent_messages_->push_back(msg);
+    return true;
+  }
+
+ private:
+  ScopedMessages* sent_messages_;
+};
+
+}  // namespace
+
+class ResourceDispatchThrottlerTest : public testing::Test,
+                                      public FakeRendererScheduler,
+                                      public ResourceDispatchThrottler {
+ public:
+  ResourceDispatchThrottlerTest()
+      : ResourceDispatchThrottler(
+            &sender_sink_,
+            this,

[davidben, 2015/02/03 19:46:48]

Having the FakeRendererScheduler and the ResourceDispatchThrottler both be
multiple-inherited in with the Test is kind of confusing. (Style guide also
prohibits non-interface multiple inheritance.) Maybe leave the
FakeRendererScheduler separate in a scoped_ptr? That'll probably require pulling
the ResourceDispatchThrottler out too since you need to pass it into the
constructor.

[jdduke (slow), 2015/02/04 01:39:50]

Yeah, I get lazy in testing code sometimes, but that's better.

+            base::TimeDelta::FromSecondsD(kFlushPeriodSeconds),
+            kRequestsPerFlush),
+        sender_sink_(&sent_messages_),
+        flush_scheduled_(false),
+        anticipate_(false),
+        last_request_id_(0) {}
+  ~ResourceDispatchThrottlerTest() override {}
+
+  // RendererScheduler implementation:
+  bool IsHighPriorityWorkAnticipated() override { return anticipate_; }
+
+ protected:
+  base::TimeTicks Now() const override { return now_; }
+
+  void ScheduleFlush() override { flush_scheduled_ = true; }
+
+  void SetHighPriorityWorkAnticipated(bool anticipate) {
+    anticipate_ = anticipate;
+  }
+
+  void Advance(base::TimeDelta delta) { now_ += delta; }
+
+  bool RunScheduledFlush() {
+    if (!flush_scheduled_)
+      return false;
+
+    flush_scheduled_ = false;
+    Flush();
+    return true;
+  }
+
+  bool RequestResource() {
+    ResourceHostMsg_Request request;
+    request.download_to_file = true;
+    return Send(new ResourceHostMsg_RequestResource(
+        kRoutingId, ++last_request_id_, request));
+  }
+
+  void RequestResourcesUntilThrottled() {
+    SetHighPriorityWorkAnticipated(true);
+    GetAndResetSentMessageCount();
+    for (RequestResource(); GetAndResetSentMessageCount(); RequestResource()) {

[davidben, 2015/02/03 19:46:48]

This looks very different from a normal for loop. Why not just:
   RequestResource();
   while (GetAndResetSentMessageCount() > 0) {
     RequestResource();
   }

[jdduke (slow), 2015/02/04 01:39:50]

Done.

+    }
+  }
+
+  bool UpdateRequestPriority(int request_id, net::RequestPriority priority) {
+    return Send(new ResourceHostMsg_DidChangePriority(request_id, priority, 0));
+  }
+
+  bool ReleaseDownloadedFile(int request_id) {
+    return Send(new ResourceHostMsg_ReleaseDownloadedFile(request_id));
+  }
+
+  bool CancelRequest(int request_id) {
+    return Send(new ResourceHostMsg_CancelRequest(request_id));
+  }
+
+  bool RequestResourceSync() {
+    SyncLoadResult result;
+    return Send(new ResourceHostMsg_SyncLoad(
+        kRoutingId, ++last_request_id_, ResourceHostMsg_Request(), &result));
+  }
+
+  size_t GetAndResetSentMessageCount() {
+    size_t sent_message_count = sent_messages_.size();
+    sent_messages_.clear();
+    return sent_message_count;
+  }
+
+  const IPC::Message* LastSentMessage() const {
+    return sent_messages_.empty() ? nullptr : sent_messages_.back();
+  }
+
+  int LastSentRequestId() const {
+    const IPC::Message* msg = LastSentMessage();
+    if (!msg)
+      return -1;
+
+    int routing_id = -1;
+    int request_id = -1;
+    PickleIterator iter(*msg);
+    CHECK(IPC::ReadParam(msg, &iter, &routing_id));
+    CHECK(IPC::ReadParam(msg, &iter, &request_id));
+    return request_id;
+  }
+
+  bool flush_scheduled() const { return flush_scheduled_; }
+
+  int last_request_id() const { return last_request_id_; }
+
+  ScopedMessages sent_messages_;
+
+ private:
+  SenderSink sender_sink_;
+  base::MessageLoopForUI message_loop_;
+  base::TimeTicks now_;
+  bool flush_scheduled_;
+  bool anticipate_;
+  int last_request_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(ResourceDispatchThrottlerTest);
+};
+
+TEST_F(ResourceDispatchThrottlerTest, NotThrottledByDefault) {
+  SetHighPriorityWorkAnticipated(false);
+  for (size_t i = 0; i < kRequestsPerFlush * 2; ++i) {
+    RequestResource();
+    EXPECT_EQ(i + 1, sent_messages_.size());
+  }
+}
+
+TEST_F(ResourceDispatchThrottlerTest, NotThrottledIfSendLimitNotReached) {
+  SetHighPriorityWorkAnticipated(true);
+  for (size_t i = 0; i < kRequestsPerFlush; ++i) {
+    RequestResource();
+    EXPECT_EQ(i + 1, sent_messages_.size());
+  }
+}
+
+TEST_F(ResourceDispatchThrottlerTest, ThrottledWhenHighPriorityWork) {
+  SetHighPriorityWorkAnticipated(true);
+  for (size_t i = 0; i < kRequestsPerFlush; ++i)
+    RequestResource();
+  ASSERT_EQ(kRequestsPerFlush, GetAndResetSentMessageCount());
+
+  RequestResource();
+  EXPECT_EQ(0U, sent_messages_.size());
+
+  EXPECT_TRUE(RunScheduledFlush());
+  EXPECT_EQ(1U, sent_messages_.size());
+}
+
+TEST_F(ResourceDispatchThrottlerTest,
+       ThrottledWhenDeferredMessageQueueNonEmpty) {
+  SetHighPriorityWorkAnticipated(true);
+  for (size_t i = 0; i < kRequestsPerFlush; ++i)
+    RequestResource();
+  ASSERT_EQ(kRequestsPerFlush, GetAndResetSentMessageCount());
+
+  RequestResource();
+  EXPECT_EQ(0U, sent_messages_.size());
+  SetHighPriorityWorkAnticipated(false);
+  RequestResource();
+  EXPECT_EQ(0U, sent_messages_.size());
+
+  EXPECT_TRUE(RunScheduledFlush());
+  EXPECT_EQ(2U, sent_messages_.size());
+}
+
+TEST_F(ResourceDispatchThrottlerTest, NotThrottledIfSufficientTimePassed) {
+  SetHighPriorityWorkAnticipated(true);
+
+  for (size_t i = 0; i < kRequestsPerFlush * 2; ++i) {
+    Advance(base::TimeDelta::FromSecondsD(kFlushPeriodSeconds * 2));
+    RequestResource();
+    EXPECT_EQ(1U, GetAndResetSentMessageCount());
+    EXPECT_FALSE(flush_scheduled());
+  }
+}
+
+TEST_F(ResourceDispatchThrottlerTest, NotThrottledIfSyncMessage) {
+  SetHighPriorityWorkAnticipated(true);
+
+  RequestResourceSync();
+  EXPECT_EQ(1U, GetAndResetSentMessageCount());
+
+  // Saturate the queue.
+  for (size_t i = 0; i < kRequestsPerFlush * 2; ++i)
+    RequestResource();
+  ASSERT_EQ(kRequestsPerFlush, GetAndResetSentMessageCount());
+
+  // Unthrottled message types should pass through untouched.
+  RequestResourceSync();
+  EXPECT_EQ(1U, GetAndResetSentMessageCount());
+  RequestResourceSync();
+  EXPECT_EQ(1U, GetAndResetSentMessageCount());
+
+  // Deferred messages should flush as usual.
+  EXPECT_TRUE(RunScheduledFlush());
+  EXPECT_EQ(kRequestsPerFlush, GetAndResetSentMessageCount());
+}
+
+TEST_F(ResourceDispatchThrottlerTest, MultipleFlushes) {
+  SetHighPriorityWorkAnticipated(true);
+  for (size_t i = 0; i < kRequestsPerFlush * 4; ++i)
+    RequestResource();
+  ASSERT_EQ(kRequestsPerFlush, GetAndResetSentMessageCount());
+
+  for (size_t i = 0; i < 3; ++i) {
+    EXPECT_TRUE(RunScheduledFlush());
+    EXPECT_EQ(kRequestsPerFlush, GetAndResetSentMessageCount()) << i;

[davidben, 2015/02/03 19:46:47]

You could probably stick a SCOPED_TRACE(i) and that'll tag both EXPECTs with i.
Ditto with some of the other cases. (You can even nest SCOPED_TRACEs. They're
fancy.)

[jdduke (slow), 2015/02/04 01:39:50]

Done.

+  }
+
+  EXPECT_FALSE(flush_scheduled());
+  EXPECT_EQ(0U, sent_messages_.size());
+}
+
+TEST_F(ResourceDispatchThrottlerTest, MultipleFlushesWhileReceiving) {
+  SetHighPriorityWorkAnticipated(true);
+  for (size_t i = 0; i < kRequestsPerFlush * 4; ++i)
+    RequestResource();
+  ASSERT_EQ(kRequestsPerFlush, GetAndResetSentMessageCount());
+
+  for (size_t i = 0; i < 3; ++i) {
+    EXPECT_TRUE(RunScheduledFlush());
+    EXPECT_EQ(kRequestsPerFlush, GetAndResetSentMessageCount()) << i;
+    for (size_t j = 0; j < kRequestsPerFlush; ++j)
+      RequestResource();
+    EXPECT_EQ(0U, sent_messages_.size()) << i;
+  }
+
+  for (size_t i = 0; i < 3; ++i) {
+    EXPECT_TRUE(RunScheduledFlush());
+    EXPECT_EQ(kRequestsPerFlush, GetAndResetSentMessageCount());
+  }
+
+  EXPECT_FALSE(flush_scheduled());
+  EXPECT_EQ(0U, sent_messages_.size());
+}
+
+TEST_F(ResourceDispatchThrottlerTest, NonRequestsNeverTriggerThrottling) {
+  RequestResource();
+  ASSERT_EQ(1U, GetAndResetSentMessageCount());
+
+  for (size_t i = 0; i < kRequestsPerFlush * 3; ++i)
+    UpdateRequestPriority(last_request_id(), net::HIGHEST);
+  EXPECT_EQ(kRequestsPerFlush * 3, sent_messages_.size());
+
+  RequestResource();
+  EXPECT_EQ(1U + kRequestsPerFlush * 3, GetAndResetSentMessageCount());
+}
+
+TEST_F(ResourceDispatchThrottlerTest, NonRequestsDeferredWhenThrottling) {
+  RequestResource();
+  ASSERT_EQ(1U, GetAndResetSentMessageCount());
+
+  RequestResourcesUntilThrottled();
+  UpdateRequestPriority(last_request_id(), net::HIGHEST);
+  ReleaseDownloadedFile(last_request_id());
+  CancelRequest(last_request_id());
+
+  EXPECT_TRUE(RunScheduledFlush());
+  EXPECT_EQ(4U, GetAndResetSentMessageCount());
+  EXPECT_FALSE(flush_scheduled());
+}
+
+TEST_F(ResourceDispatchThrottlerTest, MessageOrderingPreservedWhenThrottling) {
+  SetHighPriorityWorkAnticipated(true);
+  for (size_t i = 0; i < kRequestsPerFlush; ++i)
+    RequestResource();
+  ASSERT_EQ(kRequestsPerFlush, GetAndResetSentMessageCount());
+
+  for (size_t i = 0; i < kRequestsPerFlush; ++i) {
+    RequestResource();
+    UpdateRequestPriority(last_request_id(), net::HIGHEST);
+    CancelRequest(last_request_id() - 1);
+  }
+  ASSERT_EQ(0U, sent_messages_.size());
+
+  EXPECT_TRUE(RunScheduledFlush());
+  ASSERT_EQ(kRequestsPerFlush * 3, sent_messages_.size());
+  for (size_t i = 0; i < sent_messages_.size(); i+=3) {
+    const auto& request_msg = *sent_messages_[i];
+    const auto& priority_msg = *sent_messages_[i + 1];
+    const auto& cancel_msg = *sent_messages_[i + 2];
+
+    EXPECT_EQ(request_msg.type(), ResourceHostMsg_RequestResource::ID) << i;
+    EXPECT_EQ(priority_msg.type(), ResourceHostMsg_DidChangePriority::ID) << i;
+    EXPECT_EQ(cancel_msg.type(), ResourceHostMsg_CancelRequest::ID) << i;
+
+    EXPECT_EQ(GetRequestId(request_msg), GetRequestId(priority_msg));
+    EXPECT_EQ(GetRequestId(request_msg) - 1, GetRequestId(cancel_msg));
+  }
+  EXPECT_FALSE(flush_scheduled());
+}
+
+}  // namespace content