removed ArgByRef

cpp/include/kvikio/stream.hpp

@@ -41,32 +41,24 @@ namespace kvikio {
  *     like most other asynchronous CUDA functions that take by-value arguments.
  *
  * To support by-value arguments, we allocate the arguments on the heap (malloc `ArgByVal`) and have
- * the by-reference arguments (`ArgByRef`) points into `ArgByVal`. This way, the `read_async` and
- * `write_async` can call `.get_args()` to get the by-reference arguments required by cuFile's
- * stream API. However, this also means that the caller of `read_async` and `write_async` MUST keep
- * the returned `StreamFuture` alive until the operations is done otherwise `StreamFuture` will free
- * `ArgByVal` before cuFile had a change to use them!
+ * the by-reference argumentspoints into `ArgByVal`. This way, the `read_async` and `write_async`
+ * can call `.get_args()` to get the by-reference arguments required by cuFile's stream API.
+ * However, this also means that the caller of `read_async` and `write_async` MUST keep the returned
+ * `StreamFuture` alive until the operations is done otherwise `StreamFuture` will free `ArgByVal`
+ * before cuFile had a change to use them!
  */
 class StreamFuture {
- public:
+ private:
   struct ArgByVal {
     std::size_t size;
     off_t file_offset;
     off_t devPtr_offset;
     ssize_t bytes_done;
   };
-  struct ArgByRef {
-    std::size_t* size_p;
-    off_t* file_offset_p;
-    off_t* devPtr_offset_p;
-    ssize_t* bytes_done_p;
-  };
 
- private:
   void* _devPtr_base{nullptr};
   CUstream _stream{nullptr};
   ArgByVal* _val{nullptr};
-  ArgByRef _ref{nullptr};
 
  public:
   StreamFuture() noexcept = default;
@@ -82,10 +74,6 @@ class StreamFuture {
     }
     *_val = {
       .size = size, .file_offset = file_offset, .devPtr_offset = devPtr_offset, .bytes_done = 0};
-    _ref = {.size_p          = &_val->size,
-            .file_offset_p   = &_val->file_offset,
-            .devPtr_offset_p = &_val->devPtr_offset,
-            .bytes_done_p    = &_val->bytes_done};
   }
 
   /**
@@ -96,16 +84,14 @@ class StreamFuture {
   StreamFuture(StreamFuture&& o) noexcept
     : _devPtr_base{std::exchange(o._devPtr_base, nullptr)},
       _stream{std::exchange(o._stream, nullptr)},
-      _val{std::exchange(o._val, nullptr)},
-      _ref{o._ref}
+      _val{std::exchange(o._val, nullptr)}
   {
   }
   StreamFuture& operator=(StreamFuture&& o) noexcept
   {
     _devPtr_base = std::exchange(o._devPtr_base, nullptr);
     _stream      = std::exchange(o._stream, nullptr);
     _val         = std::exchange(o._val, nullptr);
-    _ref         = o._ref;
     return *this;
   }
 
@@ -122,12 +108,12 @@ class StreamFuture {
    */
   std::tuple<void*, std::size_t*, off_t*, off_t*, ssize_t*, CUstream> get_args() const noexcept
   {
-    return std::make_tuple(_devPtr_base,
-                           _ref.size_p,
-                           _ref.file_offset_p,
-                           _ref.devPtr_offset_p,
-                           _ref.bytes_done_p,
-                           _stream);
+    return {_devPtr_base,
+            &_val->size,
+            &_val->file_offset,
+            &_val->devPtr_offset,
+            &_val->bytes_done,
+            _stream};
   }
 
   /**
@@ -140,10 +126,10 @@ class StreamFuture {
   std::size_t check_bytes_done() const
   {
     CUDA_DRIVER_TRY(cudaAPI::instance().StreamSynchronize(_stream));
-    CUFILE_CHECK_STREAM_IO(_ref.bytes_done_p);
+    CUFILE_CHECK_STREAM_IO(&_val->bytes_done);
     // At this point, we know `*_bytes_done_p` is positive otherwise
     // CUFILE_CHECK_STREAM_IO() would have raised an exception.
-    return static_cast<std::size_t>(*_ref.bytes_done_p);
+    return static_cast<std::size_t>(_val->bytes_done);
   }
 };