Remove cached_initiator: inline WSARecv/WSASend into IOCP read_some/write_some

The cached_initiator trampoline coroutine deferred WSARecv/WSASend until
after the caller suspended, but await_suspend already guarantees the
caller's frame is saved. Inline the I/O calls directly and return
std::noop_coroutine(), matching the pattern connect() already uses.

Author: sgerbino

include/boost/corosio/detail/cached_initiator.hpp

@@ -449,64 +449,6 @@ win_socket_internal::connect(
     return std::noop_coroutine();
 }
 
-inline void
-win_socket_internal::do_read_io()
-{
-    auto& op = rd_;
-
-    op.flags = 0;
-
-    svc_.work_started();
-
-    int result = ::WSARecv(
-        socket_, op.wsabufs, op.wsabuf_count, nullptr, &op.flags, &op, nullptr);
-
-    if (result == SOCKET_ERROR)
-    {
-        DWORD err = ::WSAGetLastError();
-        if (err != WSA_IO_PENDING)
-        {
-            // Defer to avoid resuming on the initiator's stack.
-            svc_.work_finished();
-            op.dwError = err;
-            svc_.post(&op);
-            return;
-        }
-    }
-    // I/O is now pending. If stop was requested before WSARecv
-    // started, the CancelIoEx in the stop callback had nothing
-    // to cancel. Re-check and cancel the now-pending operation.
-    if (op.cancelled.load(std::memory_order_acquire))
-        ::CancelIoEx(reinterpret_cast<HANDLE>(socket_), &op);
-}
-
-inline void
-win_socket_internal::do_write_io()
-{
-    auto& op = wr_;
-
-    svc_.work_started();
-
-    int result = ::WSASend(
-        socket_, op.wsabufs, op.wsabuf_count, nullptr, 0, &op, nullptr);
-
-    if (result == SOCKET_ERROR)
-    {
-        DWORD err = ::WSAGetLastError();
-        if (err != WSA_IO_PENDING)
-        {
-            // Immediate error - must use post().
-            svc_.work_finished();
-            op.dwError = err;
-            svc_.post(&op);
-            return;
-        }
-    }
-    // Re-check cancellation after I/O is pending
-    if (op.cancelled.load(std::memory_order_acquire))
-        ::CancelIoEx(reinterpret_cast<HANDLE>(socket_), &op);
-}
-
 inline std::coroutine_handle<>
 win_socket_internal::read_some(
     std::coroutine_handle<> h,
@@ -549,8 +491,33 @@ win_socket_internal::read_some(
         op.wsabufs[i].len = static_cast<ULONG>(bufs[i].size());
     }
 
-    // Symmetric transfer to initiator - I/O starts after caller is suspended
-    return read_initiator_.start<&win_socket_internal::do_read_io>(this);
+    // Issue WSARecv directly — caller is already suspended
+    op.flags = 0;
+
+    svc_.work_started();
+
+    int result = ::WSARecv(
+        socket_, op.wsabufs, op.wsabuf_count, nullptr, &op.flags, &op,
+        nullptr);
+
+    if (result == SOCKET_ERROR)
+    {
+        DWORD err = ::WSAGetLastError();
+        if (err != WSA_IO_PENDING)
+        {
+            svc_.work_finished();
+            op.dwError = err;
+            svc_.post(&op);
+            return std::noop_coroutine();
+        }
+    }
+    // I/O is now pending. If stop was requested before WSARecv
+    // started, the CancelIoEx in the stop callback had nothing
+    // to cancel. Re-check and cancel the now-pending operation.
+    if (op.cancelled.load(std::memory_order_acquire))
+        ::CancelIoEx(reinterpret_cast<HANDLE>(socket_), &op);
+
+    return std::noop_coroutine();
 }
 
 inline std::coroutine_handle<>
@@ -593,8 +560,28 @@ win_socket_internal::write_some(
         op.wsabufs[i].len = static_cast<ULONG>(bufs[i].size());
     }
 
-    // Symmetric transfer to initiator - I/O starts after caller is suspended
-    return write_initiator_.start<&win_socket_internal::do_write_io>(this);
+    // Issue WSASend directly — caller is already suspended
+    svc_.work_started();
+
+    int result = ::WSASend(
+        socket_, op.wsabufs, op.wsabuf_count, nullptr, 0, &op, nullptr);
+
+    if (result == SOCKET_ERROR)
+    {
+        DWORD err = ::WSAGetLastError();
+        if (err != WSA_IO_PENDING)
+        {
+            svc_.work_finished();
+            op.dwError = err;
+            svc_.post(&op);
+            return std::noop_coroutine();
+        }
+    }
+    // Re-check cancellation after I/O is pending
+    if (op.cancelled.load(std::memory_order_acquire))
+        ::CancelIoEx(reinterpret_cast<HANDLE>(socket_), &op);
+
+    return std::noop_coroutine();
 }
 
 inline void

include/boost/corosio/native/detail/iocp/win_acceptor_service.hpp

@@ -19,7 +19,6 @@
 #include <boost/corosio/tcp_socket.hpp>
 #include <boost/capy/ex/executor_ref.hpp>
 #include <boost/corosio/detail/intrusive.hpp>
-#include <boost/corosio/detail/cached_initiator.hpp>
 #include <boost/corosio/native/detail/iocp/win_overlapped_op.hpp>
 #include <boost/corosio/native/detail/iocp/win_windows.hpp>
 
@@ -113,9 +112,6 @@ class win_socket_internal
     write_op wr_;
     SOCKET socket_ = INVALID_SOCKET;
 
-    cached_initiator read_initiator_;
-    cached_initiator write_initiator_;
-
 public:
     explicit win_socket_internal(win_sockets& svc) noexcept;
     ~win_socket_internal();
@@ -152,12 +148,6 @@ class win_socket_internal
     void set_socket(SOCKET s) noexcept;
     void set_endpoints(endpoint local, endpoint remote) noexcept;
 
-    /** Execute the read I/O operation (called by initiator coroutine). */
-    void do_read_io();
-
-    /** Execute the write I/O operation (called by initiator coroutine). */
-    void do_write_io();
-
 private:
     endpoint local_endpoint_;
     endpoint remote_endpoint_;