Let QUIC streams write 16k before ceding. Behind FLAG_quic_batch_writes.

net/quic/quic_write_blocked_list_test.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 "net/quic/quic_write_blocked_list.h"
 
 #include "net/quic/test_tools/quic_test_utils.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace net {
 namespace test {
 namespace {
 
 TEST(QuicWriteBlockedListTest, PriorityOrder) {
   QuicWriteBlockedList write_blocked_list;
 
   // Mark streams blocked in roughly reverse priority order, and
   // verify that streams are sorted.
-  write_blocked_list.PushBack(40,
-                              QuicWriteBlockedList::kLowestPriority);
-  write_blocked_list.PushBack(23,
-                              QuicWriteBlockedList::kHighestPriority);
-  write_blocked_list.PushBack(17,
-                              QuicWriteBlockedList::kHighestPriority);
-  write_blocked_list.PushBack(kHeadersStreamId,
-                              QuicWriteBlockedList::kHighestPriority);
-  write_blocked_list.PushBack(kCryptoStreamId,
-                              QuicWriteBlockedList::kHighestPriority);
+  write_blocked_list.AddStream(40,
+                               QuicWriteBlockedList::kLowestPriority);
+  write_blocked_list.AddStream(23,
+                               QuicWriteBlockedList::kHighestPriority);
+  write_blocked_list.AddStream(17,
+                               QuicWriteBlockedList::kHighestPriority);
+  write_blocked_list.AddStream(kHeadersStreamId,
+                               QuicWriteBlockedList::kHighestPriority);
+  write_blocked_list.AddStream(kCryptoStreamId,
+                               QuicWriteBlockedList::kHighestPriority);
 
   EXPECT_EQ(5u, write_blocked_list.NumBlockedStreams());
   EXPECT_TRUE(write_blocked_list.HasWriteBlockedCryptoOrHeadersStream());
   EXPECT_TRUE(write_blocked_list.HasWriteBlockedDataStreams());
   // The Crypto stream is highest priority.
   EXPECT_EQ(kCryptoStreamId, write_blocked_list.PopFront());
   // Followed by the Headers stream.
   EXPECT_EQ(kHeadersStreamId, write_blocked_list.PopFront());
   // Streams with same priority are popped in the order they were inserted.
   EXPECT_EQ(23u, write_blocked_list.PopFront());
   EXPECT_EQ(17u, write_blocked_list.PopFront());
   // Low priority stream appears last.
   EXPECT_EQ(40u, write_blocked_list.PopFront());
 
   EXPECT_EQ(0u, write_blocked_list.NumBlockedStreams());
   EXPECT_FALSE(write_blocked_list.HasWriteBlockedCryptoOrHeadersStream());
   EXPECT_FALSE(write_blocked_list.HasWriteBlockedDataStreams());
 }
 
 TEST(QuicWriteBlockedListTest, CryptoStream) {
   QuicWriteBlockedList write_blocked_list;
-  write_blocked_list.PushBack(kCryptoStreamId,
-                              QuicWriteBlockedList::kHighestPriority);
+  write_blocked_list.AddStream(kCryptoStreamId,
+                               QuicWriteBlockedList::kHighestPriority);
 
   EXPECT_EQ(1u, write_blocked_list.NumBlockedStreams());
   EXPECT_TRUE(write_blocked_list.HasWriteBlockedCryptoOrHeadersStream());
   EXPECT_EQ(kCryptoStreamId, write_blocked_list.PopFront());
   EXPECT_EQ(0u, write_blocked_list.NumBlockedStreams());
   EXPECT_FALSE(write_blocked_list.HasWriteBlockedCryptoOrHeadersStream());
 }
 
 TEST(QuicWriteBlockedListTest, HeadersStream) {
   QuicWriteBlockedList write_blocked_list;
-  write_blocked_list.PushBack(kHeadersStreamId,
-                              QuicWriteBlockedList::kHighestPriority);
+  write_blocked_list.AddStream(kHeadersStreamId,
+                               QuicWriteBlockedList::kHighestPriority);
 
   EXPECT_EQ(1u, write_blocked_list.NumBlockedStreams());
   EXPECT_TRUE(write_blocked_list.HasWriteBlockedCryptoOrHeadersStream());
   EXPECT_EQ(kHeadersStreamId, write_blocked_list.PopFront());
   EXPECT_EQ(0u, write_blocked_list.NumBlockedStreams());
   EXPECT_FALSE(write_blocked_list.HasWriteBlockedCryptoOrHeadersStream());
 }
 
 TEST(QuicWriteBlockedListTest, VerifyHeadersStream) {
   QuicWriteBlockedList write_blocked_list;
-  write_blocked_list.PushBack(5,
-                              QuicWriteBlockedList::kHighestPriority);
-  write_blocked_list.PushBack(kHeadersStreamId,
-                              QuicWriteBlockedList::kHighestPriority);
+  write_blocked_list.AddStream(5,
+                               QuicWriteBlockedList::kHighestPriority);
+  write_blocked_list.AddStream(kHeadersStreamId,
+                               QuicWriteBlockedList::kHighestPriority);
 
   EXPECT_EQ(2u, write_blocked_list.NumBlockedStreams());
   EXPECT_TRUE(write_blocked_list.HasWriteBlockedCryptoOrHeadersStream());
   EXPECT_TRUE(write_blocked_list.HasWriteBlockedDataStreams());
   // In newer QUIC versions, there is a headers stream which is
   // higher priority than data streams.
   EXPECT_EQ(kHeadersStreamId, write_blocked_list.PopFront());
   EXPECT_EQ(5u, write_blocked_list.PopFront());
   EXPECT_EQ(0u, write_blocked_list.NumBlockedStreams());
   EXPECT_FALSE(write_blocked_list.HasWriteBlockedCryptoOrHeadersStream());
   EXPECT_FALSE(write_blocked_list.HasWriteBlockedDataStreams());
 }
 
 TEST(QuicWriteBlockedListTest, NoDuplicateEntries) {
   // Test that QuicWriteBlockedList doesn't allow duplicate entries.
   QuicWriteBlockedList write_blocked_list;
 
   // Try to add a stream to the write blocked list multiple times at the same
   // priority.
   const QuicStreamId kBlockedId = kClientDataStreamId1;
-  write_blocked_list.PushBack(kBlockedId,
-                              QuicWriteBlockedList::kHighestPriority);
-  write_blocked_list.PushBack(kBlockedId,
-                              QuicWriteBlockedList::kHighestPriority);
-  write_blocked_list.PushBack(kBlockedId,
-                              QuicWriteBlockedList::kHighestPriority);
+  write_blocked_list.AddStream(kBlockedId,
+                               QuicWriteBlockedList::kHighestPriority);
+  write_blocked_list.AddStream(kBlockedId,
+                               QuicWriteBlockedList::kHighestPriority);
+  write_blocked_list.AddStream(kBlockedId,
+                               QuicWriteBlockedList::kHighestPriority);
 
   // This should only result in one blocked stream being added.
   EXPECT_EQ(1u, write_blocked_list.NumBlockedStreams());
   EXPECT_TRUE(write_blocked_list.HasWriteBlockedDataStreams());
 
   // There should only be one stream to pop off the front.
   EXPECT_EQ(kBlockedId, write_blocked_list.PopFront());
   EXPECT_EQ(0u, write_blocked_list.NumBlockedStreams());
   EXPECT_FALSE(write_blocked_list.HasWriteBlockedDataStreams());
 }
 
+TEST(QuicWriteBlockedListTest, BatchingWrites) {
+  FLAGS_quic_batch_writes = true;
+  QuicWriteBlockedList write_blocked_list;
+
+  const QuicStreamId id1 = kClientDataStreamId1;
+  const QuicStreamId id2 = kClientDataStreamId2;
+
+  write_blocked_list.AddStream(id1, QuicWriteBlockedList::kLowestPriority);
+  write_blocked_list.AddStream(id2, QuicWriteBlockedList::kLowestPriority);
+  EXPECT_EQ(2u, write_blocked_list.NumBlockedStreams());
+
+  // The first stream we push back should stay at the front until 16k is
+  // written.
+  EXPECT_EQ(id1, write_blocked_list.PopFront());
+  write_blocked_list.UpdateBytesForStream(id1, 15999);
+  write_blocked_list.AddStream(id1, QuicWriteBlockedList::kLowestPriority);
+  EXPECT_EQ(2u, write_blocked_list.NumBlockedStreams());
+  EXPECT_EQ(id1, write_blocked_list.PopFront());
+
+  // Once 16k is written the first stream will cede to the next.
+  write_blocked_list.UpdateBytesForStream(id1, 1);
+  write_blocked_list.AddStream(id1, QuicWriteBlockedList::kLowestPriority);
+  EXPECT_EQ(2u, write_blocked_list.NumBlockedStreams());
+  EXPECT_EQ(id2, write_blocked_list.PopFront());
+
+  // Set the new stream to have written all but one byte.
+  write_blocked_list.UpdateBytesForStream(id2, 15999);
+  write_blocked_list.AddStream(id2, QuicWriteBlockedList::kLowestPriority);
+  EXPECT_EQ(2u, write_blocked_list.NumBlockedStreams());
+
+  // Ensure higher priority streams are popped first.
+  const QuicStreamId id3 = kClientDataStreamId2 + 2;
+  write_blocked_list.AddStream(id3, QuicWriteBlockedList::kHighestPriority);
+  EXPECT_EQ(id3, write_blocked_list.PopFront());
+
+  // Higher priority streams will always be popped first, even if using their
+  // byte quota
+  write_blocked_list.UpdateBytesForStream(id1, 20000);
+  write_blocked_list.AddStream(id3, QuicWriteBlockedList::kHighestPriority);
+  EXPECT_EQ(id3, write_blocked_list.PopFront());
+
+  // Once the higher priority stream is out of the way, id2 will resume its 16k
+  // write, with only 1 byte remaining of its guaranteed write allocation.
+  EXPECT_EQ(id2, write_blocked_list.PopFront());
+  write_blocked_list.UpdateBytesForStream(id2, 1);
+  write_blocked_list.AddStream(id2, QuicWriteBlockedList::kLowestPriority);
+  EXPECT_EQ(2u, write_blocked_list.NumBlockedStreams());
+  EXPECT_EQ(id1, write_blocked_list.PopFront());
+}
+
 }  // namespace
 }  // namespace test
 }  // namespace net