Add lastByteStreamOffset to WtBufferedStreamData::DequeueResult

Summary:
Populate lastByteStreamOffset in dequeue() from the completed PendingWrite's offset field, and add test coverage in WtStreamManager::DeliveryCallback verifying the correct offset is reported for each dequeue scenario.

X-link: facebook/proxygen#600

Reviewed By: hanidamlaj

Differential Revision: D95707692

Pulled By: afrind

fbshipit-source-id: 40ad112bdcc0bf0584c0f00c960e9890ea35cc82

Author: afrind

third-party/proxygen/src/proxygen/lib/http/webtransport/WtEgressContainer.cpp

@@ -76,6 +76,8 @@ WtBufferedStreamData::DequeueResult WtBufferedStreamData::dequeue(
   }
 
   window_.commit(resQueue.chainLength());
+  res.lastByteStreamOffset =
+      std::max<uint64_t>(window_.getCurrentOffset(), 1) - 1;
   res.data = resQueue.move();
   return res;
 }

third-party/proxygen/src/proxygen/lib/http/webtransport/WtEgressContainer.h

@@ -106,6 +106,7 @@ class WtBufferedStreamData {
     std::unique_ptr<folly::IOBuf> data;
     bool fin{false};
     WebTransport::ByteEventCallback* deliveryCallback{nullptr};
+    uint64_t lastByteStreamOffset{0};
   };
 
   /**

third-party/proxygen/src/proxygen/lib/http/webtransport/test/WtStreamManagerTest.cpp

@@ -1139,6 +1139,7 @@ TEST(WtStreamManager, DeliveryCallback) {
   EXPECT_EQ(deq1.data->computeChainDataLength(), 100);
   EXPECT_TRUE(deq1.fin);
   EXPECT_EQ(deq1.deliveryCallback, &cb1);
+  EXPECT_EQ(deq1.lastByteStreamOffset, 99);
 
   // multiple writes with different callbacks
   auto* h2 = CHECK_NOTNULL(streamManager.createEgressHandle());
@@ -1149,15 +1150,18 @@ TEST(WtStreamManager, DeliveryCallback) {
   auto d2a = streamManager.dequeue(*h2, 100);
   EXPECT_EQ(d2a.data->computeChainDataLength(), 100);
   EXPECT_EQ(d2a.deliveryCallback, &cb1);
+  EXPECT_EQ(d2a.lastByteStreamOffset, 99);
 
   auto d2b = streamManager.dequeue(*h2, 100);
   EXPECT_EQ(d2b.data->computeChainDataLength(), 50);
   EXPECT_EQ(d2b.deliveryCallback, &cb2);
+  EXPECT_EQ(d2b.lastByteStreamOffset, 149);
 
   auto d2c = streamManager.dequeue(*h2, 100);
   EXPECT_EQ(d2c.data->computeChainDataLength(), 75);
   EXPECT_TRUE(d2c.fin);
   EXPECT_EQ(d2c.deliveryCallback, &cb3);
+  EXPECT_EQ(d2c.lastByteStreamOffset, 224);
 
   // writes without callbacks coalesce with final callback write
   auto* h3 = CHECK_NOTNULL(streamManager.createEgressHandle());
@@ -1169,6 +1173,7 @@ TEST(WtStreamManager, DeliveryCallback) {
   EXPECT_EQ(deq3.data->computeChainDataLength(), 250);
   EXPECT_TRUE(deq3.fin);
   EXPECT_EQ(deq3.deliveryCallback, &cb4);
+  EXPECT_EQ(deq3.lastByteStreamOffset, 249);
 
   // callback delivered only when write completes
   auto* h4 = CHECK_NOTNULL(streamManager.createEgressHandle());
@@ -1177,24 +1182,28 @@ TEST(WtStreamManager, DeliveryCallback) {
   auto d4a = streamManager.dequeue(*h4, 60);
   EXPECT_EQ(d4a.data->computeChainDataLength(), 60);
   EXPECT_EQ(d4a.deliveryCallback, nullptr);
+  EXPECT_EQ(d4a.lastByteStreamOffset, 59);
 
   auto d4b = streamManager.dequeue(*h4, 60);
   EXPECT_EQ(d4b.data->computeChainDataLength(), 40);
   EXPECT_TRUE(d4b.fin);
   EXPECT_EQ(d4b.deliveryCallback, &cb5);
+  EXPECT_EQ(d4b.lastByteStreamOffset, 99);
 
   // fin-only write with callback
   auto* h5 = CHECK_NOTNULL(streamManager.createEgressHandle());
   h5->writeStreamData(makeBuf(50), /*fin=*/false, nullptr);
   auto d5a = streamManager.dequeue(*h5, 100);
   EXPECT_EQ(d5a.data->computeChainDataLength(), 50);
   EXPECT_EQ(d5a.deliveryCallback, nullptr);
+  EXPECT_EQ(d5a.lastByteStreamOffset, 49);
 
   h5->writeStreamData(nullptr, /*fin=*/true, &cb1);
   auto d5b = streamManager.dequeue(*h5, 100);
   EXPECT_EQ(d5b.data->computeChainDataLength(), 0);
   EXPECT_TRUE(d5b.fin);
   EXPECT_EQ(d5b.deliveryCallback, &cb1);
+  EXPECT_EQ(d5b.lastByteStreamOffset, 49);
 }
 
 TEST(WtStreamManager, ByteEventCancellation) {