Improve documentation on lifetime of message and status

1 files changed, 42 insertions, 1 deletions

diff --git a/include/grpcpp/impl/codegen/async_stream.h b/include/grpcpp/impl/codegen/async_stream.h
index b2134590c3..cd433e4869 100644
--- a/include/grpcpp/impl/codegen/async_stream.h
+++ b/include/grpcpp/impl/codegen/async_stream.h
@@ -64,7 +64,7 @@ class ClientAsyncStreamingInterface {
   ///     earlier call to \a AsyncReaderInterface::Read that yielded a failed
   ///     result, e.g. cq->Next(&read_tag, &ok) filled in 'ok' with 'false').
   ///
-  /// This function will return when either:
+  /// The tag will be returned when either:
   /// - all incoming messages have been read and the server has returned
   ///   a status.
   /// - the server has returned a non-OK status.
@@ -112,6 +112,8 @@ class AsyncWriterInterface {
   /// Only one write may be outstanding at any given time. This means that
   /// after calling Write, one must wait to receive \a tag from the completion
   /// queue BEFORE calling Write again.
+  /// GRPC doesn't take ownership or a reference to \a msg, so it is safe to
+  /// to deallocate once Write returns.
   /// This is thread-safe with respect to \a AsyncReaderInterface::Read
   ///
   /// \param[in] msg The message to be written.
@@ -124,6 +126,8 @@ class AsyncWriterInterface {
   /// Only one write may be outstanding at any given time. This means that
   /// after calling Write, one must wait to receive \a tag from the completion
   /// queue BEFORE calling Write again.
+  /// GRPC doesn't take ownership or a reference to \a msg, so it is safe to
+  /// to deallocate once Write returns.
   /// WriteOptions \a options is used to set the write options of this message.
   /// This is thread-safe with respect to \a AsyncReaderInterface::Read
   ///
@@ -143,6 +147,8 @@ class AsyncWriterInterface {
   /// and write is initiated. Note that WriteLast can only buffer \a msg up to
   /// the flow control window size. If \a msg size is larger than the window
   /// size, it will be sent on wire without buffering.
+  /// GRPC doesn't take ownership or a reference to \a msg, so it is safe to
+  /// to deallocate once Write returns.
   ///
   /// \param[in] msg The message to be written.
   /// \param[in] options The WriteOptions to be used to write this message.
@@ -629,6 +635,8 @@ class ServerAsyncReaderInterface
   /// This operation will end when the server has finished sending out initial
   /// metadata (if not sent already), response message, and status, or if
   /// some failure occurred when trying to do so.
+  /// GRPC doesn't take ownership or a reference to \a msg or \a status, so it
+  /// is safe to to deallocate once Finish returns.
   ///
   /// \param[in] tag Tag identifying this request.
   /// \param[in] status To be sent to the client as the result of this call.
@@ -650,6 +658,9 @@ class ServerAsyncReaderInterface
   /// metadata (if not sent already), and status, or if some failure occurred
   /// when trying to do so.
   ///
+  /// GRPC doesn't take ownership or a reference to \a status, so it is safe to
+  /// to deallocate once FinishWithError returns.
+  ///
   /// \param[in] tag Tag identifying this request.
   /// \param[in] status To be sent to the client as the result of this call.
   ///     - Note: \a status must have a non-OK code.
@@ -697,6 +708,9 @@ class ServerAsyncReader final : public ServerAsyncReaderInterface<W, R> {
   ///     initial and trailing metadata.
   ///
   /// Note: \a msg is not sent if \a status has a non-OK code.
+  ///
+  /// GRPC doesn't take ownership or a reference to \a msg and \a status, so it
+  /// is safe to to deallocate once Finish returns.
   void Finish(const W& msg, const Status& status, void* tag) override {
     finish_ops_.set_output_tag(tag);
     if (!ctx_->sent_initial_metadata_) {
@@ -723,6 +737,9 @@ class ServerAsyncReader final : public ServerAsyncReaderInterface<W, R> {
   ///   - also sends initial metadata if not alreay sent.
   ///   - uses the \a ServerContext associated with this call to send possible
   ///     initial and trailing metadata.
+  ///
+  /// GRPC doesn't take ownership or a reference to \a status, so it is safe to
+  /// to deallocate once FinishWithError returns.
   void FinishWithError(const Status& status, void* tag) override {
     GPR_CODEGEN_ASSERT(!status.ok());
     finish_ops_.set_output_tag(tag);
@@ -773,6 +790,9 @@ class ServerAsyncWriterInterface
   /// metadata (if not sent already), response message, and status, or if
   /// some failure occurred when trying to do so.
   ///
+  /// GRPC doesn't take ownership or a reference to \a status, so it is safe to
+  /// to deallocate once Finish returns.
+  ///
   /// \param[in] tag Tag identifying this request.
   /// \param[in] status To be sent to the client as the result of this call.
   virtual void Finish(const Status& status, void* tag) = 0;
@@ -784,6 +804,9 @@ class ServerAsyncWriterInterface
   /// WriteAndFinish is equivalent of performing WriteLast and Finish
   /// in a single step.
   ///
+  /// GRPC doesn't take ownership or a reference to \a msg and \a status, so it
+  /// is safe to to deallocate once WriteAndFinish returns.
+  ///
   /// \param[in] msg The message to be written.
   /// \param[in] options The WriteOptions to be used to write this message.
   /// \param[in] status The Status that server returns to client.
@@ -847,6 +870,9 @@ class ServerAsyncWriter final : public ServerAsyncWriterInterface<W> {
   ///     for sending trailing (and initial) metadata to the client.
   ///
   /// Note: \a status must have an OK code.
+  ///
+  /// GRPC doesn't take ownership or a reference to \a msg and \a status, so it
+  /// is safe to to deallocate once WriteAndFinish returns.
   void WriteAndFinish(const W& msg, WriteOptions options, const Status& status,
                       void* tag) override {
     write_ops_.set_output_tag(tag);
@@ -865,6 +891,9 @@ class ServerAsyncWriter final : public ServerAsyncWriterInterface<W> {
   ///
   /// Note: there are no restrictions are the code of
   /// \a status,it may be non-OK
+  ///
+  /// GRPC doesn't take ownership or a reference to \a status, so it is safe to
+  /// to deallocate once Finish returns.
   void Finish(const Status& status, void* tag) override {
     finish_ops_.set_output_tag(tag);
     EnsureInitialMetadataSent(&finish_ops_);
@@ -924,6 +953,9 @@ class ServerAsyncReaderWriterInterface
   /// metadata (if not sent already), response message, and status, or if some
   /// failure occurred when trying to do so.
   ///
+  /// GRPC doesn't take ownership or a reference to \a status, so it is safe to
+  /// to deallocate once Finish returns.
+  ///
   /// \param[in] tag Tag identifying this request.
   /// \param[in] status To be sent to the client as the result of this call.
   virtual void Finish(const Status& status, void* tag) = 0;
@@ -935,6 +967,9 @@ class ServerAsyncReaderWriterInterface
   /// WriteAndFinish is equivalent of performing WriteLast and Finish in a
   /// single step.
   ///
+  /// GRPC doesn't take ownership or a reference to \a msg and \a status, so it
+  /// is safe to to deallocate once WriteAndFinish returns.
+  ///
   /// \param[in] msg The message to be written.
   /// \param[in] options The WriteOptions to be used to write this message.
   /// \param[in] status The Status that server returns to client.
@@ -1006,6 +1041,9 @@ class ServerAsyncReaderWriter final
   ///     for sending trailing (and initial) metadata to the client.
   ///
   /// Note: \a status must have an OK code.
+  //
+  /// GRPC doesn't take ownership or a reference to \a msg and \a status, so it
+  /// is safe to to deallocate once WriteAndFinish returns.
   void WriteAndFinish(const W& msg, WriteOptions options, const Status& status,
                       void* tag) override {
     write_ops_.set_output_tag(tag);
@@ -1024,6 +1062,9 @@ class ServerAsyncReaderWriter final
   ///
   /// Note: there are no restrictions are the code of \a status,
   /// it may be non-OK
+  //
+  /// GRPC doesn't take ownership or a reference to \a status, so it is safe to
+  /// to deallocate once Finish returns.
   void Finish(const Status& status, void* tag) override {
     finish_ops_.set_output_tag(tag);
     EnsureInitialMetadataSent(&finish_ops_);