support: implementation of io timer source

Author: frankist

include/srsran/support/io/io_timer_source.h

@@ -0,0 +1,40 @@
+/*
+ *
+ * Copyright 2021-2024 Software Radio Systems Limited
+ *
+ * By using this file, you agree to the terms and conditions set
+ * forth in the LICENSE file which can be found at the top level of
+ * the distribution.
+ *
+ */
+
+#pragma once
+
+#include "srsran/support/io/io_broker.h"
+#include "srsran/support/io/unique_fd.h"
+#include "srsran/support/timers.h"
+
+namespace srsran {
+
+/// \brief Interface for a timer source.
+class io_timer_source
+{
+public:
+  io_timer_source(timer_manager&            tick_sink_,
+                  io_broker&                broker_,
+                  std::chrono::milliseconds tick_period = std::chrono::milliseconds{1});
+
+private:
+  void read_time();
+
+  timer_manager&            tick_sink;
+  io_broker&                broker;
+  std::chrono::milliseconds tick_period;
+  srslog::basic_logger&     logger;
+
+  unique_fd timer_fd;
+
+  io_broker::subscriber io_sub;
+};
+
+} // namespace srsran

lib/support/network/CMakeLists.txt

@@ -10,6 +10,7 @@ add_library(srsran_network
         transport_layer_address.cpp
         io_broker_factory.cpp
         io_broker_epoll.cpp
+        io_timer_source.cpp
         sctp_socket.cpp
         sockets.cpp)
 target_link_libraries(srsran_network srslog)

lib/support/network/io_timer_source.cpp

@@ -0,0 +1,52 @@
+/*
+ *
+ * Copyright 2021-2024 Software Radio Systems Limited
+ *
+ * By using this file, you agree to the terms and conditions set
+ * forth in the LICENSE file which can be found at the top level of
+ * the distribution.
+ *
+ */
+
+#include "srsran/support/io/io_timer_source.h"
+#include "srsran/support/error_handling.h"
+#include "srsran/support/io/io_broker.h"
+#include "srsran/support/timers.h"
+#include <sys/timerfd.h>
+
+using namespace srsran;
+
+io_timer_source::io_timer_source(timer_manager&            tick_sink_,
+                                 io_broker&                broker_,
+                                 std::chrono::milliseconds tick_period_) :
+  tick_sink(tick_sink_), broker(broker_), tick_period(tick_period_), logger(srslog::fetch_basic_logger("IO-EPOLL"))
+{
+  timer_fd = unique_fd{timerfd_create(CLOCK_REALTIME, 0)};
+  if (not timer_fd.is_open()) {
+    report_fatal_error_if_not("Failed to create timer source (errno={})", strerror(errno));
+  }
+
+  struct itimerspec timerspec = {{0, 0},
+                                 {std::chrono::duration_cast<std::chrono::seconds>(tick_period).count(),
+                                  std::chrono::duration_cast<std::chrono::nanoseconds>(tick_period).count()}};
+  timerfd_settime(timer_fd.value(), 0, &timerspec, nullptr);
+
+  io_sub = broker.register_fd(
+      timer_fd.value(), [this]() { read_time(); }, [this](io_broker::error_code ev) { io_sub.reset(); });
+}
+
+void io_timer_source::read_time()
+{
+  char read_buffer[8];
+  int  n = read(timer_fd.value(), read_buffer, sizeof(read_buffer));
+  if (n < 0) {
+    logger.error("Failed to read timerfd (errno={})", strerror(errno));
+    return;
+  }
+  if (n == 0) {
+    logger.warning("Timerfd read returned 0");
+  }
+
+  // Tick timers.
+  tick_sink.tick();
+}