transport: Implement an I/O service that uses an offload thread

The offload_io_service executes another I/O service instance within an
offload thread, and provides synchronization mechanisms to communicate
with clients. Frame buffers are passed from the offload thread to the
client and back via single-producer, single-consumer queues.

1 files changed, 66 insertions, 0 deletions

diff --git a/host/lib/include/uhdlib/transport/offload_io_service.hpp b/host/lib/include/uhdlib/transport/offload_io_service.hpp
new file mode 100644
index 000000000..a7d9d211d
--- /dev/null
+++ b/host/lib/include/uhdlib/transport/offload_io_service.hpp
@@ -0,0 +1,66 @@
+//
+// Copyright 2019 Ettus Research, a National Instruments brand
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+
+#ifndef INCLUDED_UHDLIB_TRANSPORT_OFFLOAD_IO_SERVICE_HPP
+#define INCLUDED_UHDLIB_TRANSPORT_OFFLOAD_IO_SERVICE_HPP
+
+#include <uhdlib/transport/io_service.hpp>
+
+namespace uhd { namespace transport {
+
+/*!
+ * I/O service with offload thread
+ *
+ * Note: This I/O service can only be used with transports that allow releasing
+ * frame buffers out of order, since flow control packets are handled entirely
+ * within the offload thread.
+ */
+class offload_io_service : public io_service
+{
+public:
+    enum client_type_t
+    {
+        RECV_ONLY,
+        SEND_ONLY,
+        BOTH_SEND_AND_RECV
+    };
+
+    enum wait_mode_t
+    {
+        POLL,
+        BLOCK
+    };
+
+    /*!
+     * Options for configuring offload I/O service
+     */
+    struct params_t
+    {
+        //! Array of CPU numbers to which to affinitize the offload thread.
+        std::vector<size_t> cpu_affinity_list;
+        //! The types of client that the I/O service needs to support.
+        client_type_t client_type = BOTH_SEND_AND_RECV;
+        //! The thread behavior when waiting for incoming packets If set to
+        //! BLOCK, the client type must be set to either RECV_ONLY or SEND_ONLY.
+        wait_mode_t wait_mode = POLL;
+    };
+
+    /*!
+     * Creates an io service that offloads I/O to a worker thread and
+     * passes configuration parameters to it.
+     *
+     *  \param io_srv The io service to perform the actual work in the worker
+     *                thread.
+     *  \param params Parameters to pass to the offload I/O service.
+     *  \return A composite I/O service that executes the provided io service
+     *          in its own thread.
+     */
+    static sptr make(io_service::sptr io_srv, const params_t& params);
+};
+
+}} // namespace uhd::transport
+
+#endif /* INCLUDED_UHDLIB_TRANSPORT_OFFLOAD_IO_SERVICE_HPP */