topic.c

/***********************************************************************************
 * @file        topic.c                                                            *
 * @brief       Implementation of the Topic-based Publish/Subscribe system.        *
 *                                                                                 *
 * @{                                                                              *
 ***********************************************************************************/
 
#include "_topic.h"
#include "topic.h"
 
#include "FreeRTOS.h"
#include "queue.h"
 
/*
 * TODO:
 * Add argument for topic message length. Messages on topics should be packaged
 * by the publish/comment methods into structs containing the data and a field
 * defining the length of the received data in subscription and publication
 * inboxes.
 */
 
/* =============================================================================== */
bool Topic_comment(Topic *topic, uint8_t *comment) {
  // Early return if invalid argument
  if (topic == NULL || comment == NULL)
    return false;
 
  // Send comment data to author queue
  xQueueSend(topic->commentInbox, comment, 2);
  return true; // Returns true if args were valid and send was attempted
}
 
/* =============================================================================== */
bool Topic_publish(PrivateTopic *topic, uint8_t *article) {
  // Early return if invalid argument
  if (topic == NULL || article == NULL)
    return false;
 
  // Calculate first and last addresses in subscription list
  const QueueHandle_t *start = topic->subscriptions;
  const QueueHandle_t *end   = topic->subscriptions + topic->numSubscriptions;
 
  // Send article data to each subscriber queue in the list
  for (const QueueHandle_t *entry = start; entry < end; entry++) {
    // Check if the retrieved handle is valid before sending
    // (Subscribers are responsible for creating their queues)
    if (entry != NULL)
      // Send data to the subscriber's queue (non-blocking)
      xQueueSend(*entry, article, 0);
 
    // Silently ignore if the handle is NULL
    // (subscriber might not have created queue yet/correctly)
  }
  return true; // Returns true if args were valid and loop completed
}