Make an allBytesAckedTill function

Summary: With reliable resets, we can only safely close a stream once all bytes until the reliable size have been ACKed by the peer. We're going to use this helper function to aid us in that.

Reviewed By: mjoras

Differential Revision: D66781309

fbshipit-source-id: 66094929b53c9eab3185e05b8a033b112577b60b

quic/state/StreamData.h

@@ -345,6 +345,15 @@ struct QuicStreamLike {
       pendingWrites.splitAtMost(pendingWrites.chainLength());
     }
   }
+
+  [[nodiscard]] bool allBytesAckedTill(uint64_t offset) const {
+    if (ackedIntervals.empty()) {
+      return false;
+    }
+
+    return ackedIntervals.front().start == 0 &&
+        ackedIntervals.front().end >= offset;
+  }
 };
 
 struct QuicConnectionStateBase;

quic/state/test/StreamDataTest.cpp

@@ -585,4 +585,49 @@ TEST(StreamDataTest, WriteBufferMetaRemovalNoChange) {
   EXPECT_EQ(state.writeBufMeta.length, 12);
 }
 
+TEST(StreamDataTest, AllBytesAckedTillEmptyAck) {
+  QuicConnectionStateBase qcsb(QuicNodeType::Client);
+  QuicStreamState state(0, qcsb);
+
+  EXPECT_TRUE(state.ackedIntervals.empty());
+  EXPECT_EQ(state.allBytesAckedTill(0), false);
+}
+
+TEST(StreamDataTest, AllBytesAckedTillNotStartAtZero) {
+  QuicConnectionStateBase qcsb(QuicNodeType::Client);
+  QuicStreamState state(0, qcsb);
+
+  EXPECT_TRUE(state.ackedIntervals.empty());
+  state.updateAckedIntervals(1, 5, false);
+  EXPECT_EQ(state.allBytesAckedTill(5), false);
+}
+
+TEST(StreamDataTest, AllBytesAckedTillNotEnoughLength) {
+  QuicConnectionStateBase qcsb(QuicNodeType::Client);
+  QuicStreamState state(0, qcsb);
+
+  EXPECT_TRUE(state.ackedIntervals.empty());
+  state.updateAckedIntervals(0, 5, false);
+  EXPECT_EQ(state.allBytesAckedTill(5), false);
+}
+
+TEST(StreamDataTest, AllBytesAckedPass) {
+  QuicConnectionStateBase qcsb(QuicNodeType::Client);
+  QuicStreamState state(0, qcsb);
+
+  EXPECT_TRUE(state.ackedIntervals.empty());
+  state.updateAckedIntervals(0, 6, false);
+  EXPECT_EQ(state.allBytesAckedTill(5), true);
+}
+
+TEST(StreamDataTest, AllBytesAckedDisjointIntervals) {
+  QuicConnectionStateBase qcsb(QuicNodeType::Client);
+  QuicStreamState state(0, qcsb);
+
+  EXPECT_TRUE(state.ackedIntervals.empty());
+  state.updateAckedIntervals(0, 2, false);
+  state.updateAckedIntervals(3, 5, false);
+  EXPECT_EQ(state.allBytesAckedTill(5), false);
+}
+
 } // namespace quic::test