Re-sync with internal repository (#494)

The internal and external repositories are out of sync. This Pull Request attempts to brings them back in sync by patching the GitHub repository. Please carefully review this patch. You must disable ShipIt for your project in order to merge this pull request. DO NOT IMPORT this pull request. Instead, merge it directly on GitHub using the MERGE BUTTON. Re-enable ShipIt after merging.

Author: facebook-github-bot

proxygen/lib/http/codec/HTTP2Codec.cpp

@@ -433,7 +433,18 @@ ErrorCode HTTP2Codec::parseHeadersImpl(
     const folly::Optional<http2::PriorityUpdate>& priority,
     const folly::Optional<uint32_t>& promisedStream,
     const folly::Optional<ExAttributes>& exAttributes) {
-  curHeaderBlock_.append(std::move(headerBuf));
+  if (curHeader_.type == http2::FrameType::CONTINUATION && headerBuf) {
+    constexpr size_t kMinTailroomForUnshare = 1024;
+    if (!curHeaderBlock_.empty() &&
+        curHeaderBlock_.front()->prev()->isSharedOne() &&
+        headerBuf->prev()->tailroom() > kMinTailroomForUnshare) {
+      // tail of the current block is shared, but tail of new block has ample
+      // space.  Unshare tail of the new buf to allow future packing
+      headerBuf->prev()->unshareOne();
+    }
+  }
+  curHeaderBlock_.append(
+      std::move(headerBuf), /*pack=*/true, /*reuseTail=*/false);
   std::unique_ptr<HTTPMessage> msg;
   uint32_t headersCompleteStream = curHeader_.stream;
 

proxygen/lib/http/codec/test/HTTP2CodecTest.cpp

@@ -1006,6 +1006,28 @@ TEST_F(HTTP2CodecTest, BasicContinuation) {
   EXPECT_EQ(callbacks_.sessionErrors, 0);
 }
 
+TEST_F(HTTP2CodecTest, ContinuationChain) {
+  auto settings = (HTTPSettings*)upstreamCodec_.getIngressSettings();
+  settings->setSetting(SettingsId::MAX_FRAME_SIZE, 3);
+
+  HTTPMessage req = getBigGetRequest();
+  auto id = upstreamCodec_.createStream();
+  upstreamCodec_.generateHeader(output_, id, req);
+
+  parse();
+  callbacks_.expectMessage(false, -1, "/");
+#ifndef NDEBUG
+  EXPECT_GT(downstreamCodec_.getReceivedFrameCount(), 1);
+#endif
+  const auto& headers = callbacks_.msg->getHeaders();
+  EXPECT_EQ("coolio", headers.getSingleOrEmpty(HTTP_HEADER_USER_AGENT));
+  EXPECT_EQ(callbacks_.messageBegin, 1);
+  EXPECT_EQ(callbacks_.headersComplete, 1);
+  EXPECT_EQ(callbacks_.messageComplete, 0);
+  EXPECT_EQ(callbacks_.streamErrors, 0);
+  EXPECT_EQ(callbacks_.sessionErrors, 0);
+}
+
 TEST_F(HTTP2CodecTest, BasicContinuationEndStream) {
   // CONTINUATION with END_STREAM flag set on the preceding HEADERS frame
   HTTPMessage req = getBigGetRequest();