io/uring/Ring: add io_uring_submit_and_wait_timeout() wrapper

src/io/uring/Queue.cxx

@@ -90,4 +90,15 @@ Queue::WaitDispatchOneCompletion()
 	return true;
 }
 
+bool
+Queue::SubmitAndWaitDispatchOneCompletion(struct __kernel_timespec &timeout)
+{
+	auto *cqe = ring.SubmitAndWaitCompletion(timeout);
+	if (cqe == nullptr)
+		return false;
+
+	DispatchOneCompletion(*cqe);
+	return true;
+}
+
 } // namespace Uring

src/io/uring/Queue.hxx

@@ -101,6 +101,8 @@ public:
 		while (WaitDispatchOneCompletion()) {}
 	}
 
+	bool SubmitAndWaitDispatchOneCompletion(struct __kernel_timespec &timeout);
+
 private:
 	void DispatchOneCompletion(struct io_uring_cqe &cqe) noexcept;
 };

src/io/uring/Ring.cxx

@@ -60,6 +60,21 @@ Ring::WaitCompletion()
 	return cqe;
 }
 
+struct io_uring_cqe *
+Ring::SubmitAndWaitCompletion(struct __kernel_timespec &timeout)
+{
+	struct io_uring_cqe *cqe;
+	if (int error = io_uring_submit_and_wait_timeout(&ring, &cqe, 1, &timeout, nullptr);
+	    error < 0) {
+		if (error == -ETIME || error == -EAGAIN)
+			return nullptr;
+
+		throw MakeErrno(-error, "io_uring_submit_and_wait_timeout() failed");
+	}
+
+	return cqe;
+}
+
 struct io_uring_cqe *
 Ring::PeekCompletion()
 {

src/io/uring/Ring.hxx

@@ -101,6 +101,16 @@ public:
 	 */
 	struct io_uring_cqe *WaitCompletion();
 
+	/**
+	 * Submit requests and wait for one completion (or a timeout).
+	 * Wrapper for io_uring_submit_and_wait_timeout().
+	 *
+	 * Throws on error.
+	 *
+	 * @return a completion queue entry or nullptr on EAGAIN/ETIME
+	 */
+	struct io_uring_cqe *SubmitAndWaitCompletion(struct __kernel_timespec &timeout);
+
 	/**
 	 * Peek one completion (non-blocking).
 	 *