iobufqueue diediedie

Summary:
Don't use IOBufQueue for most operations in mvfst and use BufQueue instead. Since BufQueue did not support a splitAtMost, added it in instead.

The only place that we still use IOBufQueue is in crypto because fizz still requires it

Reviewed By: mjoras

Differential Revision: D18846960

fbshipit-source-id: 4320b7f8614f8d2c75f6de0e6b786d33650e9656

quic/api/QuicTransportFunctions.cpp

@@ -96,7 +96,8 @@ void handleNewStreamDataWritten(
   // Idealy we should also check this data doesn't exist in either retx buffer
   // or loss buffer, but that's an expensive search.
   stream.currentWriteOffset += frameLen;
-  auto bufWritten = stream.writeBuffer.split(folly::to<size_t>(frameLen));
+  auto bufWritten = stream.writeBuffer.splitAtMost(folly::to<size_t>(frameLen));
+  DCHECK_EQ(bufWritten->computeChainDataLength(), frameLen);
   stream.currentWriteOffset += frameFin ? 1 : 0;
   CHECK(stream.retransmissionBuffer
             .emplace(
@@ -126,7 +127,7 @@ void handleRetransmissionWritten(
     stream.lossBuffer.erase(lossBufferIter);
   } else {
     lossBufferIter->offset += frameLen;
-    bufWritten = lossBufferIter->data.split(frameLen);
+    bufWritten = lossBufferIter->data.splitAtMost(frameLen);
   }
   CHECK(stream.retransmissionBuffer
             .emplace(

quic/api/test/CMakeLists.txt

@@ -16,6 +16,7 @@ quic_add_test(TARGET QuicTransportTest
   QuicTransportTest.cpp
   DEPENDS
   Folly::folly
+  mvfst_bufutil
   mvfst_transport
   mvfst_server
   mvfst_state_stream_functions

quic/api/test/QuicTransportTest.cpp

@@ -11,11 +11,11 @@
 
 #include <folly/Random.h>
 #include <folly/io/Cursor.h>
-#include <folly/io/IOBufQueue.h>
 #include <folly/io/async/test/MockAsyncUDPSocket.h>
 #include <quic/api/QuicTransportBase.h>
 #include <quic/api/QuicTransportFunctions.h>
 #include <quic/api/test/Mocks.h>
+#include <quic/common/BufUtil.h>
 #include <quic/common/Timers.h>
 #include <quic/common/test/TestUtils.h>
 #include <quic/handshake/test/Mocks.h>
@@ -307,7 +307,7 @@ void verifyCorrectness(
   EXPECT_EQ(finExpected, finSet);
   // Verify retransmissionBuffer:
   EXPECT_FALSE(stream->retransmissionBuffer.empty());
-  IOBufQueue retxBufCombined;
+  BufQueue retxBufCombined;
   std::vector<StreamBuffer> rtxCopy;
   for (auto& itr : stream->retransmissionBuffer) {
     rtxCopy.push_back(StreamBuffer(
@@ -380,9 +380,6 @@ TEST_F(QuicTransportTest, NotAppLimitedWithLoss) {
   auto stream = transport_->createBidirectionalStream().value();
   auto lossStream = transport_->createBidirectionalStream().value();
   conn.streamManager->addLoss(lossStream);
-  conn.streamManager->getStream(lossStream)
-      ->lossBuffer.emplace_back(
-          IOBuf::copyBuffer("Mountains may depart"), 0, false);
   transport_->writeChain(
       stream,
       IOBuf::copyBuffer("An elephant sitting still"),

quic/client/CMakeLists.txt

@@ -26,6 +26,7 @@ target_compile_options(
 
 add_dependencies(
   mvfst_client
+  mvfst_bufutil
   mvfst_flowcontrol
   mvfst_happyeyeballs
   mvfst_loss

quic/client/QuicClientTransport.cpp

@@ -96,7 +96,7 @@ QuicClientTransport::~QuicClientTransport() {
 void QuicClientTransport::processUDPData(
     const folly::SocketAddress& peer,
     NetworkDataSingle&& networkData) {
-  folly::IOBufQueue udpData{folly::IOBufQueue::cacheChainLength()};
+  BufQueue udpData;
   udpData.append(std::move(networkData.data));
 
   if (!conn_->version) {
@@ -129,7 +129,7 @@ void QuicClientTransport::processUDPData(
 void QuicClientTransport::processPacketData(
     const folly::SocketAddress& peer,
     TimePoint receiveTimePoint,
-    folly::IOBufQueue& packetQueue) {
+    BufQueue& packetQueue) {
   auto packetSize = packetQueue.chainLength();
   if (packetSize == 0) {
     return;

quic/client/QuicClientTransport.h

@@ -15,6 +15,7 @@
 #include <quic/api/QuicTransportBase.h>
 #include <quic/client/handshake/QuicPskCache.h>
 #include <quic/client/state/ClientStateMachine.h>
+#include <quic/common/BufUtil.h>
 
 namespace quic {
 
@@ -159,7 +160,7 @@ class QuicClientTransport
   void processPacketData(
       const folly::SocketAddress& peer,
       TimePoint receiveTimePoint,
-      folly::IOBufQueue& packetQueue);
+      BufQueue& packetQueue);
 
   void startCryptoHandshake();
 

quic/client/test/CMakeLists.txt

@@ -13,6 +13,7 @@ quic_add_test(TARGET QuicClientTransportTest
   DEPENDS
   Folly::folly
   ${LIBGMOCK_LIBRARIES}
+  mvfst_bufutil
   mvfst_client
   mvfst_codec_types
   mvfst_handshake

quic/client/test/QuicClientTransportTest.cpp

@@ -338,7 +338,7 @@ class QuicClientTransportIntegrationTest : public TestWithParam<TestingParams> {
 
 class StreamData {
  public:
-  folly::IOBufQueue data{folly::IOBufQueue::cacheChainLength()};
+  BufQueue data;
 
   folly::Promise<StreamPair> promise;
   StreamId id;
@@ -3115,7 +3115,7 @@ TEST_F(QuicClientTransportAfterStartTest, ReadStreamCoalescedMany) {
   auto expected = IOBuf::copyBuffer("hello");
   EXPECT_CALL(readCb, readAvailable(streamId)).Times(0);
   FizzCryptoFactory cryptoFactory;
-  IOBufQueue packets{IOBufQueue::cacheChainLength()};
+  BufQueue packets;
   for (int i = 0; i < kMaxNumCoalescedPackets; i++) {
     auto garbage = IOBuf::copyBuffer("garbage");
     auto initialCipher = cryptoFactory.getServerInitialCipher(

quic/codec/CMakeLists.txt

@@ -189,6 +189,7 @@ target_compile_options(
 
 add_dependencies(
   mvfst_codec
+  mvfst_bufutil
   mvfst_constants
   mvfst_codec_decode
   mvfst_codec_types

quic/codec/Decode.cpp

@@ -337,7 +337,7 @@ ReadStreamFrame decodeStreamFrame(
     }
     // If dataLength > data's actual length then the cursor will throw.
     queue.trimStart(cursor - queue.front());
-    data = queue.split(dataLength->first);
+    data = queue.splitAtMost(dataLength->first);
   } else {
     // Missing Data Length field doesn't mean no data. It means the rest of the
     // frame are all data.

quic/codec/QuicPacketBuilder.h

@@ -37,7 +37,7 @@ constexpr auto kLongHeaderHeaderSize = sizeof(uint8_t) /* Type bytes */ +
 constexpr auto kCipherOverheadHeuristic = 16;
 
 // TODO: i'm sure this isn't the optimal value:
-// IOBufQueue growth byte size for in PacketBuilder:
+// Appender growth byte size for in PacketBuilder:
 constexpr size_t kAppenderGrowthSize = 100;
 
 class PacketBuilderInterface {

quic/codec/QuicReadCodec.cpp

@@ -23,7 +23,7 @@ namespace quic {
 QuicReadCodec::QuicReadCodec(QuicNodeType nodeType) : nodeType_(nodeType) {}
 
 folly::Optional<VersionNegotiationPacket>
-QuicReadCodec::tryParsingVersionNegotiation(folly::IOBufQueue& queue) {
+QuicReadCodec::tryParsingVersionNegotiation(BufQueue& queue) {
   folly::io::Cursor cursor(queue.front());
   if (!cursor.canAdvance(sizeof(uint8_t))) {
     return folly::none;
@@ -47,7 +47,7 @@ QuicReadCodec::tryParsingVersionNegotiation(folly::IOBufQueue& queue) {
 }
 
 CodecResult QuicReadCodec::parseLongHeaderPacket(
-    folly::IOBufQueue& queue,
+    BufQueue& queue,
     const AckStates& ackStates) {
   folly::io::Cursor cursor(queue.front());
   auto initialByte = cursor.readBE<uint8_t>();
@@ -57,7 +57,7 @@ CodecResult QuicReadCodec::parseLongHeaderPacket(
     // We've failed to parse the long header, so we have no idea where this
     // packet ends. Clear the queue since no other data in this packet is
     // parse-able.
-    queue.clear();
+    queue.move();
     return CodecResult(Nothing());
   }
   if (longHeaderInvariant->invariant.version ==
@@ -67,7 +67,7 @@ CodecResult QuicReadCodec::parseLongHeaderPacket(
     // function.
     // Since VN is not allowed to be coalesced with another packet
     // type, we clear out the buffer to avoid anyone else parsing it.
-    queue.clear();
+    queue.move();
     return CodecResult(Nothing());
   }
   auto type = parseLongHeaderType(initialByte);
@@ -79,7 +79,7 @@ CodecResult QuicReadCodec::parseLongHeaderPacket(
     // We've failed to parse the long header, so we have no idea where this
     // packet ends. Clear the queue since no other data in this packet is
     // parse-able.
-    queue.clear();
+    queue.move();
     return CodecResult(Nothing());
   }
   // As soon as we have parsed out the long header we can split off any
@@ -96,10 +96,10 @@ CodecResult QuicReadCodec::parseLongHeaderPacket(
       packetNumberOffset + parsedLongHeader->packetLength.packetLength;
   if (queue.chainLength() < currentPacketLen) {
     // Packet appears truncated, there's no parse-able data left.
-    queue.clear();
+    queue.move();
     return CodecResult(Nothing());
   }
-  auto currentPacketData = queue.split(currentPacketLen);
+  auto currentPacketData = queue.splitAtMost(currentPacketLen);
   cursor.reset(currentPacketData.get());
   cursor.skip(packetNumberOffset);
   // Sample starts after the max packet number size. This ensures that we
@@ -108,7 +108,7 @@ CodecResult QuicReadCodec::parseLongHeaderPacket(
     VLOG(4) << "Dropping packet, not enough for packet number "
             << connIdToHex();
     // Packet appears truncated, there's no parse-able data left.
-    queue.clear();
+    queue.move();
     return CodecResult(Nothing());
   }
   cursor.skip(kMaxPacketNumEncodingSize);
@@ -116,7 +116,7 @@ CodecResult QuicReadCodec::parseLongHeaderPacket(
   if (!cursor.canAdvance(sample.size())) {
     VLOG(4) << "Dropping packet, sample too small " << connIdToHex();
     // Packet appears truncated, there's no parse-able data left.
-    queue.clear();
+    queue.move();
     return CodecResult(Nothing());
   }
   cursor.pull(sample.data(), sample.size());
@@ -197,10 +197,10 @@ CodecResult QuicReadCodec::parseLongHeaderPacket(
       initialByteRange.data()[0], packetNumberByteRange, expectedNextPacketNum);
 
   longHeader.setPacketNumber(packetNum.first);
-  folly::IOBufQueue decryptQueue{folly::IOBufQueue::cacheChainLength()};
+  BufQueue decryptQueue;
   decryptQueue.append(std::move(currentPacketData));
   size_t aadLen = packetNumberOffset + packetNum.second;
-  auto headerData = decryptQueue.split(aadLen);
+  auto headerData = decryptQueue.splitAtMost(aadLen);
   // parsing verifies that packetLength >= packet number length.
   auto encryptedData = decryptQueue.splitAtMost(
       parsedLongHeader->packetLength.packetLength - packetNum.second);
@@ -233,7 +233,7 @@ CodecResult QuicReadCodec::parseLongHeaderPacket(
 }
 
 CodecResult QuicReadCodec::parsePacket(
-    folly::IOBufQueue& queue,
+    BufQueue& queue,
     const AckStates& ackStates,
     size_t dstConnIdSize) {
   if (queue.empty()) {
@@ -272,7 +272,7 @@ CodecResult QuicReadCodec::parsePacket(
     VLOG(10) << "Dropping packet, too small for sample " << connIdToHex();
     // There's not enough space for the short header packet, clear the queue
     // to indicate there's no more parse-able data.
-    queue.clear();
+    queue.move();
     return CodecResult(Nothing());
   }
   // Take it out of the queue so we can do some writing.

quic/codec/QuicReadCodec.h

@@ -13,6 +13,7 @@
 #include <quic/codec/PacketNumber.h>
 #include <quic/codec/PacketNumberCipher.h>
 #include <quic/codec/Types.h>
+#include <quic/common/BufUtil.h>
 #include <quic/handshake/Aead.h>
 #include <quic/state/AckStates.h>
 
@@ -94,7 +95,7 @@ class QuicReadCodec {
    * before the version is negotiated to detect VN.
    */
   virtual CodecResult parsePacket(
-      folly::IOBufQueue& queue,
+      BufQueue& queue,
       const AckStates& ackStates,
       size_t dstConnIdSize = kDefaultConnectionIdSize);
 
@@ -105,7 +106,7 @@ class QuicReadCodec {
    * a VN packet or is invalid.
    */
   folly::Optional<VersionNegotiationPacket> tryParsingVersionNegotiation(
-      folly::IOBufQueue& queue);
+      BufQueue& queue);
 
   const Aead* getOneRttReadCipher() const;
   const Aead* getZeroRttReadCipher() const;
@@ -151,7 +152,7 @@ class QuicReadCodec {
 
  private:
   CodecResult parseLongHeaderPacket(
-      folly::IOBufQueue& queue,
+      BufQueue& queue,
       const AckStates& ackStates);
 
   std::string connIdToHex();

quic/codec/test/CMakeLists.txt

@@ -32,6 +32,7 @@ quic_add_test(TARGET QuicWriteCodecTest
   QuicWriteCodecTest.cpp
   DEPENDS
   Folly::folly
+  mvfst_bufutil
   mvfst_codec
   mvfst_codec_decode
   mvfst_codec_types

quic/codec/test/QuicReadCodecTest.cpp

@@ -124,6 +124,37 @@ TEST_F(QuicReadCodecTest, RetryPacketTest) {
   EXPECT_EQ(headerOut.getToken(), expected);
 }
 
+TEST_F(QuicReadCodecTest, LongHeaderPacketLenMismatch) {
+  LongHeader headerIn(
+      LongHeader::Types::Initial,
+      getTestConnectionId(70),
+      getTestConnectionId(90),
+      321,
+      QuicVersion::MVFST,
+      std::string("fluffydog"),
+      getTestConnectionId(110));
+
+  RegularQuicPacketBuilder builder(
+      kDefaultUDPSendPacketLen, std::move(headerIn), 0 /* largestAcked */);
+  builder.setCipherOverhead(0);
+  writeCryptoFrame(0, folly::IOBuf::copyBuffer("CHLO"), builder);
+  auto packet = packetToBuf(std::move(builder).buildPacket());
+  auto packetQueue = bufToQueue(std::move(packet));
+
+  auto tmp = packetQueue.move();
+  tmp->coalesce();
+  tmp->trimEnd(1);
+  packetQueue.append(std::move(tmp));
+
+  AckStates ackStates;
+  auto codec = makeUnencryptedCodec();
+  codec->setInitialReadCipher(createNoOpAead());
+  codec->setInitialHeaderCipher(test::createNoOpHeaderCipher());
+  auto result = codec->parsePacket(packetQueue, ackStates);
+  auto nothing = result.nothing();
+  EXPECT_NE(nothing, nullptr);
+}
+
 TEST_F(QuicReadCodecTest, EmptyVersionNegotiationPacketTest) {
   auto srcConnId = getTestConnectionId(0), destConnId = getTestConnectionId(1);
   std::vector<QuicVersion> versions;

quic/codec/test/QuicWriteCodecTest.cpp

@@ -9,13 +9,13 @@
 #include <quic/codec/QuicWriteCodec.h>
 #include <folly/Random.h>
 #include <folly/io/Cursor.h>
-#include <folly/io/IOBufQueue.h>
 #include <folly/portability/GMock.h>
 #include <folly/portability/GTest.h>
 #include <quic/QuicException.h>
 #include <quic/codec/Decode.h>
 #include <quic/codec/Types.h>
 #include <quic/codec/test/Mocks.h>
+#include <quic/common/BufUtil.h>
 #include <quic/common/test/TestUtils.h>
 
 using namespace quic;

quic/common/BufUtil.cpp

@@ -4,13 +4,10 @@
 
 namespace quic {
 
-Buf BufQueue::split(size_t len) {
+Buf BufQueue::splitAtMost(size_t len) {
   Buf result;
   folly::IOBuf* current = chain_.get();
-  if (current == nullptr && len > 0) {
-    throw std::underflow_error(
-        "Attempt to remove more bytes than are present in BufQueue");
-  } else if (current == nullptr) {
+  if (current == nullptr) {
     DCHECK_EQ(chainLength_, 0);
     return folly::IOBuf::create(0);
   }
@@ -43,12 +40,16 @@ Buf BufQueue::split(size_t len) {
     }
     current = current->next();
     if (current == chain_.get()) {
-      throw std::underflow_error(
-          "Attempt to remove more bytes than are present in BufQueue");
+      break;
     }
   }
-  chainLength_ -= len;
-  DCHECK(chainLength_ == 0 || chain_);
+  if (remaining > 0) {
+    // We did not find all the data we needed, so we are going to consume the
+    // entire chain instead.
+    result = std::move(chain_);
+  }
+  chainLength_ -= (len - remaining);
+  DCHECK_EQ(chainLength_, chain_ ? chain_->computeChainDataLength() : 0);
   if (UNLIKELY(result == nullptr)) {
     return folly::IOBuf::create(0);
   }

quic/common/BufUtil.h

@@ -50,7 +50,7 @@ class BufQueue {
     return chain_.get();
   }
 
-  Buf split(size_t n);
+  Buf splitAtMost(size_t n);
 
   size_t trimStartAtMost(size_t amount);
 

quic/common/test/BufUtilTest.cpp

@@ -78,55 +78,59 @@ TEST(BufQueue, Split) {
   checkConsistency(queue);
   EXPECT_EQ(12, queue.front()->computeChainDataLength());
 
-  unique_ptr<IOBuf> prefix(queue.split(1));
+  unique_ptr<IOBuf> prefix(queue.splitAtMost(1));
   checkConsistency(queue);
   EXPECT_EQ(1, prefix->computeChainDataLength());
   EXPECT_EQ(11, queue.front()->computeChainDataLength());
-  prefix = queue.split(2);
+  prefix = queue.splitAtMost(2);
   checkConsistency(queue);
   EXPECT_EQ(2, prefix->computeChainDataLength());
   EXPECT_EQ(9, queue.front()->computeChainDataLength());
-  prefix = queue.split(3);
+  prefix = queue.splitAtMost(3);
   checkConsistency(queue);
   EXPECT_EQ(3, prefix->computeChainDataLength());
   EXPECT_EQ(6, queue.front()->computeChainDataLength());
-  prefix = queue.split(1);
+  prefix = queue.splitAtMost(1);
   checkConsistency(queue);
   EXPECT_EQ(1, prefix->computeChainDataLength());
   EXPECT_EQ(5, queue.front()->computeChainDataLength());
-  prefix = queue.split(5);
+  prefix = queue.splitAtMost(5);
   checkConsistency(queue);
   EXPECT_EQ(5, prefix->computeChainDataLength());
   EXPECT_EQ((IOBuf*)nullptr, queue.front());
 
   queue.append(IOBuf::copyBuffer(SCL("Hello,")));
-  prefix = queue.split(3);
+  prefix = queue.splitAtMost(3);
   EXPECT_EQ(3, prefix->computeChainDataLength());
   EXPECT_EQ(3, queue.chainLength());
   checkConsistency(queue);
 
   queue.append(IOBuf::copyBuffer(SCL(" World")));
   checkConsistency(queue);
-  EXPECT_THROW({ prefix = queue.split(13); }, std::underflow_error);
+
+  prefix = queue.splitAtMost(13);
+  EXPECT_EQ(9, prefix->computeChainDataLength());
+  EXPECT_EQ(0, queue.chainLength());
   checkConsistency(queue);
 }
 
 TEST(BufQueue, SplitZero) {
   BufQueue queue;
   queue.append(IOBuf::copyBuffer(SCL("Hello world")));
-  auto buf = queue.split(0);
+  auto buf = queue.splitAtMost(0);
   EXPECT_EQ(buf->computeChainDataLength(), 0);
 }
 
 TEST(BufQueue, SplitEmpty) {
   BufQueue queue;
-  auto buf = queue.split(0);
+  auto buf = queue.splitAtMost(0);
   EXPECT_EQ(buf->computeChainDataLength(), 0);
 }
 
-TEST(BufQueue, SplitEmptyInvalid) {
+TEST(BufQueue, SplitEmptt) {
   BufQueue queue;
-  EXPECT_THROW(queue.split(1), std::underflow_error);
+  auto res = queue.splitAtMost(1);
+  EXPECT_EQ(res->computeChainDataLength(), 0);
 }
 
 TEST(BufQueue, TrimStartAtMost) {

quic/common/test/TestUtils.cpp

@@ -556,8 +556,8 @@ CongestionController::AckEvent makeAck(
   return ack;
 }
 
-folly::IOBufQueue bufToQueue(Buf buf) {
-  folly::IOBufQueue queue{folly::IOBufQueue::cacheChainLength()};
+BufQueue bufToQueue(Buf buf) {
+  BufQueue queue;
   buf->coalesce();
   queue.append(std::move(buf));
   return queue;

quic/common/test/TestUtils.h

@@ -11,6 +11,7 @@
 #include <quic/client/handshake/QuicPskCache.h>
 #include <quic/codec/QuicPacketBuilder.h>
 #include <quic/codec/Types.h>
+#include <quic/common/BufUtil.h>
 #include <quic/handshake/test/Mocks.h>
 #include <quic/logging/FileQLogger.h>
 #include <quic/server/state/ServerStateMachine.h>
@@ -224,7 +225,7 @@ CongestionController::AckEvent makeAck(
     TimePoint ackedTime,
     TimePoint sendTime);
 
-folly::IOBufQueue bufToQueue(Buf buf);
+BufQueue bufToQueue(Buf buf);
 
 StatelessResetToken generateStatelessResetToken();
 

quic/samples/echo/EchoClient.h

@@ -19,6 +19,7 @@
 #include <quic/api/QuicSocket.h>
 #include <quic/client/QuicClientTransport.h>
 #include <quic/client/handshake/FizzClientQuicHandshakeContext.h>
+#include <quic/common/BufUtil.h>
 #include <quic/common/test/TestUtils.h>
 
 namespace quic {
@@ -155,7 +156,7 @@ class EchoClient : public quic::QuicSocket::ConnectionCallback,
   ~EchoClient() override = default;
 
  private:
-  void sendMessage(quic::StreamId id, folly::IOBufQueue& data) {
+  void sendMessage(quic::StreamId id, BufQueue& data) {
     auto message = data.move();
     auto res = quicClient_->writeChain(id, message->clone(), true, false);
     if (res.hasError()) {
@@ -178,7 +179,7 @@ class EchoClient : public quic::QuicSocket::ConnectionCallback,
   uint16_t port_;
   bool prEnabled_;
   std::shared_ptr<quic::QuicClientTransport> quicClient_;
-  std::map<quic::StreamId, folly::IOBufQueue> pendingOutput_;
+  std::map<quic::StreamId, BufQueue> pendingOutput_;
   std::map<quic::StreamId, uint64_t> recvOffsets_;
 };
 } // namespace samples

quic/samples/echo/EchoHandler.h

@@ -10,8 +10,8 @@
 
 #include <quic/api/QuicSocket.h>
 
-#include <folly/io/IOBufQueue.h>
 #include <folly/io/async/EventBase.h>
+#include <quic/common/BufUtil.h>
 
 namespace quic {
 namespace samples {
@@ -19,7 +19,7 @@ class EchoHandler : public quic::QuicSocket::ConnectionCallback,
                     public quic::QuicSocket::ReadCallback,
                     public quic::QuicSocket::WriteCallback {
  public:
-  using StreamData = std::pair<folly::IOBufQueue, bool>;
+  using StreamData = std::pair<BufQueue, bool>;
 
   explicit EchoHandler(folly::EventBase* evbIn, bool prEnabled = false)
       : evb(evbIn), prEnabled_(prEnabled) {}
@@ -62,10 +62,7 @@ class EchoHandler : public quic::QuicSocket::ConnectionCallback,
       return;
     }
     if (input_.find(id) == input_.end()) {
-      input_.emplace(
-          id,
-          std::make_pair(
-              folly::IOBufQueue(folly::IOBufQueue::cacheChainLength()), false));
+      input_.emplace(id, std::make_pair(BufQueue(), false));
     }
     quic::Buf data = std::move(res.value().first);
     bool eof = res.value().second;
@@ -145,7 +142,7 @@ class EchoHandler : public quic::QuicSocket::ConnectionCallback,
       }
     }
 
-    originalData.split(toSplit);
+    originalData.splitAtMost(toSplit);
 
     auto res = sock->writeChain(id, originalData.move(), true, false, nullptr);
     if (res.hasError()) {

quic/server/state/ServerStateMachine.cpp

@@ -8,6 +8,7 @@
 
 #include <quic/server/state/ServerStateMachine.h>
 
+#include <quic/common/BufUtil.h>
 #include <quic/congestion_control/CongestionControllerFactory.h>
 #include <quic/flowcontrol/QuicFlowController.h>
 #include <quic/handshake/FizzCryptoFactory.h>
@@ -604,7 +605,7 @@ void onServerReadDataFromOpen(
         initialDestinationConnectionId, version);
     conn.peerAddress = conn.originalPeerAddress;
   }
-  folly::IOBufQueue udpData{folly::IOBufQueue::cacheChainLength()};
+  BufQueue udpData;
   udpData.append(std::move(readData.networkData.data));
   for (uint16_t processedPackets = 0;
        !udpData.empty() && processedPackets < kMaxNumCoalescedPackets;
@@ -1043,7 +1044,7 @@ void onServerReadDataFromClosed(
     QuicServerConnectionState& conn,
     ServerEvents::ReadData& readData) {
   CHECK_EQ(conn.state, ServerState::Closed);
-  folly::IOBufQueue udpData{folly::IOBufQueue::cacheChainLength()};
+  BufQueue udpData;
   udpData.append(std::move(readData.networkData.data));
   auto packetSize = udpData.empty() ? 0 : udpData.chainLength();
   if (!conn.readCodec) {

quic/server/test/QuicSocketTest.cpp

@@ -10,7 +10,6 @@
 #include <quic/api/test/MockQuicSocket.h>
 #include <quic/samples/echo/EchoHandler.h>
 
-#include <folly/io/IOBufQueue.h>
 #include <folly/io/async/EventBase.h>
 
 #include <gtest/gtest.h>

quic/state/QuicStreamFunctions.cpp

@@ -248,7 +248,8 @@ std::pair<Buf, bool> readDataInOrderFromReadBuffer(
     if (sinkData) {
       curr->data.trimStart(toRead);
     } else {
-      splice = curr->data.split(toRead);
+      splice = curr->data.splitAtMost(toRead);
+      DCHECK_EQ(splice->computeChainDataLength(), toRead);
     }
     curr->offset += toRead;
     if (curr->data.chainLength() == 0) {

quic/state/StateData.h

@@ -10,7 +10,6 @@
 
 #include <folly/Optional.h>
 #include <folly/io/IOBuf.h>
-#include <folly/io/IOBufQueue.h>
 #include <folly/io/async/AsyncUDPSocket.h>
 #include <folly/io/async/HHWheelTimer.h>
 #include <quic/QuicConstants.h>