Return bool in BiDi stream callbacks

Summary: In practice each callback implementation has to track its own state, in which case the only important information captured by this return value is whether the calling object is still alive (as otherwise it can just check its state member for the rest of the information).

Reviewed By: sazonovkirill

Differential Revision: D79906351

fbshipit-source-id: 898b5cc44130a5ef7bb2e4e37a3bba6a2c2f5c5f

Author: iahs

third-party/thrift/src/thrift/lib/cpp2/async/StreamCallbacks.h

@@ -422,6 +422,11 @@ struct BiDiChannelState {
   bool sinkAlive() const {
     return state_ != State::OnlyStreamOpen && state_ != State::Closed;
   }
+  bool anyAlive() const { return state_ != State::Closed; }
+  bool bothAlive() const {
+    return state_ == State::StreamAndSinkOpen ||
+        state_ == State::AwaitingFirstResponse;
+  }
 
   BiDiChannelState& markFirstResponseSent() {
     if (state_ == State::AwaitingFirstResponse) {
@@ -467,13 +472,12 @@ class BiDiServerCallback {
  public:
   virtual ~BiDiServerCallback() = default;
 
-  FOLLY_NODISCARD virtual BiDiChannelState onStreamRequestN(uint64_t) = 0;
-  FOLLY_NODISCARD virtual BiDiChannelState onStreamCancel() = 0;
+  FOLLY_NODISCARD virtual bool onStreamRequestN(uint64_t) = 0;
+  FOLLY_NODISCARD virtual bool onStreamCancel() = 0;
 
-  FOLLY_NODISCARD virtual BiDiChannelState onSinkNext(StreamPayload&&) = 0;
-  FOLLY_NODISCARD virtual BiDiChannelState onSinkError(
-      folly::exception_wrapper) = 0;
-  FOLLY_NODISCARD virtual BiDiChannelState onSinkComplete() = 0;
+  FOLLY_NODISCARD virtual bool onSinkNext(StreamPayload&&) = 0;
+  FOLLY_NODISCARD virtual bool onSinkError(folly::exception_wrapper) = 0;
+  FOLLY_NODISCARD virtual bool onSinkComplete() = 0;
 
   virtual void resetClientCallback(BiDiClientCallback&) = 0;
 };
@@ -482,26 +486,30 @@ class BiDiClientCallback {
  public:
   virtual ~BiDiClientCallback() = default;
 
-  FOLLY_NODISCARD virtual BiDiChannelState onFirstResponse(
+  FOLLY_NODISCARD virtual bool onFirstResponse(
       FirstResponsePayload&&, folly::EventBase*, BiDiServerCallback*) = 0;
   virtual void onFirstResponseError(folly::exception_wrapper) = 0;
 
-  FOLLY_NODISCARD virtual BiDiChannelState onStreamNext(StreamPayload&&) = 0;
-  FOLLY_NODISCARD virtual BiDiChannelState onStreamError(
-      folly::exception_wrapper) = 0;
-  FOLLY_NODISCARD virtual BiDiChannelState onStreamComplete() = 0;
+  FOLLY_NODISCARD virtual bool onStreamNext(StreamPayload&&) = 0;
+  FOLLY_NODISCARD virtual bool onStreamError(folly::exception_wrapper) = 0;
+  FOLLY_NODISCARD virtual bool onStreamComplete() = 0;
 
-  FOLLY_NODISCARD virtual BiDiChannelState onSinkRequestN(uint64_t) = 0;
-  FOLLY_NODISCARD virtual BiDiChannelState onSinkCancel() = 0;
+  FOLLY_NODISCARD virtual bool onSinkRequestN(uint64_t) = 0;
+  FOLLY_NODISCARD virtual bool onSinkCancel() = 0;
 
   virtual void resetServerCallback(BiDiServerCallback&) = 0;
 };
 
 struct BiDiServerCallbackCancel {
   void operator()(BiDiServerCallback* biDiServerCallback) noexcept {
-    auto state = biDiServerCallback->onStreamCancel();
-    // This should be handled as an early close.
-    DCHECK(!state.sinkAlive() && !state.streamAlive());
+    auto alive = biDiServerCallback->onStreamCancel();
+    if (alive) {
+      TApplicationException ex(
+          TApplicationException::TApplicationExceptionType::INTERRUPTION,
+          "BiDi server callback canceled");
+      alive = biDiServerCallback->onSinkError(std::move(ex));
+    }
+    DCHECK(!alive);
   }
 };