nuttx/net/udp/udp_notifier.c

/****************************************************************************
 * net/udp/udp_notifier.c
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>
#include <assert.h>

#include <nuttx/wqueue.h>
#include <nuttx/mm/iob.h>

#include "udp/udp.h"

#ifdef CONFIG_NET_UDP_NOTIFIER

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: udp_readahead_notifier_setup
 *
 * Description:
 *   Set up to perform a callback to the worker function when an UDP data
 *   is added to the read-ahead buffer.  The worker function will execute
 *   on the low priority worker thread.
 *
 * Input Parameters:
 *   worker - The worker function to execute on the low priority work
 *            queue when data is available in the UDP read-ahead buffer.
 *   conn  - The UDP connection where read-ahead data is needed.
 *   arg    - A user-defined argument that will be available to the worker
 *            function when it runs.
 *
 * Returned Value:
 *   > 0   - The notification is in place.  The returned value is a key that
 *           may be used later in a call to udp_notifier_teardown().
 *   == 0  - There is already buffered read-ahead data.  No notification
 *           will be provided.
 *   < 0   - An unexpected error occurred and notification will occur.  The
 *           returned value is a negated errno value that indicates the
 *           nature of the failure.
 *
 ****************************************************************************/

int udp_readahead_notifier_setup(worker_t worker,
                                 FAR struct udp_conn_s *conn,
                                 FAR void *arg)
{
  struct work_notifier_s info;

  DEBUGASSERT(worker != NULL);

  /* If there is already buffered read-ahead data, then return zero without
   * setting up the notification.
   */

  if (conn->readahead.qh_head != NULL)
    {
      return 0;
    }

  /* Otherwise, this is just a simple wrapper around work_notifer_setup(). */

  info.evtype    = WORK_UDP_READAHEAD;
  info.qid       = LPWORK;
  info.qualifier = conn;
  info.arg       = arg;
  info.worker    = worker;

  return work_notifier_setup(&info);
}

/****************************************************************************
 * Name: udp_writebuffer_notifier_setup
 *
 * Description:
 *   Set up to perform a callback to the worker function when an UDP write
 *   buffer is emptied.  The worker function will execute on the high
 *   priority worker thread.
 *
 * Input Parameters:
 *   worker - The worker function to execute on the low priority work
 *            queue when data is available in the UDP read-ahead buffer.
 *   conn  - The UDP connection where read-ahead data is needed.
 *   arg    - A user-defined argument that will be available to the worker
 *            function when it runs.
 *
 * Returned Value:
 *   > 0   - The notification is in place.  The returned value is a key that
 *           may be used later in a call to udp_notifier_teardown().
 *   == 0  - There is already buffered read-ahead data.  No notification
 *           will be provided.
 *   < 0   - An unexpected error occurred and no notification will occur.
 *           The returned value is a negated errno value that indicates the
 *           nature of the failure.
 *
 ****************************************************************************/

int udp_writebuffer_notifier_setup(worker_t worker,
                                   FAR struct udp_conn_s *conn,
                                   FAR void *arg)
{
#ifdef CONFIG_NET_UDP_WRITE_BUFFERS
  struct work_notifier_s info;

  DEBUGASSERT(worker != NULL);

  /* If there is already buffered read-ahead data, then return zero without
   * setting up the notification.
   */

  if (sq_empty(&conn->write_q))
    {
      return 0;
    }

  /* Otherwise, this is just a simple wrapper around work_notifer_setup(). */

  info.evtype    = WORK_UDP_WRITEBUFFER;
  info.qid       = LPWORK;
  info.qualifier = conn;
  info.arg       = arg;
  info.worker    = worker;

  return work_notifier_setup(&info);
#else
  return 0;
#endif
}

/****************************************************************************
 * Name: udp_notifier_teardown
 *
 * Description:
 *   Eliminate a UDP read-ahead notification previously setup by
 *   udp_readahead_notifier_setup().  This function should only be called if
 *   the notification should be aborted prior to the notification.  The
 *   notification will automatically be torn down after the notification.
 *
 * Input Parameters:
 *   key - The key value returned from a previous call to
 *         udp_readahead_notifier_setup().
 *
 * Returned Value:
 *   Zero (OK) is returned on success; a negated errno value is returned on
 *   any failure.
 *
 ****************************************************************************/

int udp_notifier_teardown(int key)
{
  /* This is just a simple wrapper around work_notifier_teardown(). */

  return work_notifier_teardown(key);
}

/****************************************************************************
 * Name: udp_readahead_signal
 *
 * Description:
 *   Read-ahead data has been buffered.  Notify all threads waiting for
 *   read-ahead data to become available.
 *
 *   When read-ahead data becomes available, *all* of the workers waiting
 *   for read-ahead data will be executed.  If there are multiple workers
 *   waiting for read-ahead data then only the first to execute will get the
 *   data.
 *   Others will need to call udp_readahead_notifier_setup() once again.
 *
 * Input Parameters:
 *   conn  - The UDP connection where read-ahead data was just buffered.
 *
 * Returned Value:
 *   None.
 *
 ****************************************************************************/

void udp_readahead_signal(FAR struct udp_conn_s *conn)
{
  /* This is just a simple wrapper around work_notifier_signal(). */

  work_notifier_signal(WORK_UDP_READAHEAD, conn);
}

/****************************************************************************
 * Name: udp_writebuffer_signal
 *
 * Description:
 *   All buffer Tx data has been sent.  Signal all threads waiting for the
 *   write buffers to become empty.
 *
 *   When write buffer becomes empty, *all* of the workers waiting
 *   for that event data will be executed.  If there are multiple workers
 *   waiting for read-ahead data then only the first to execute will get the
 *   data.  Others will need to call tcp_writebuffer_notifier_setup() once
 *   again.
 *
 * Input Parameters:
 *   conn  - The UDP connection where read-ahead data was just buffered.
 *
 * Returned Value:
 *   None.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_UDP_WRITE_BUFFERS
void udp_writebuffer_signal(FAR struct udp_conn_s *conn)
{
  /* This is just a simple wrapper around work_notifier_signal(). */

  work_notifier_signal(WORK_UDP_WRITEBUFFER, conn);
}
#endif

#endif /* CONFIG_NET_UDP_NOTIFIER */