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/*
* FreeRTOS V202112.00
* Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
* https://www.FreeRTOS.org
* https://github.com/FreeRTOS
*
*/
/**
* @file subscription_manager.h
* @brief Functions for managing MQTT subscriptions.
*/
#ifndef SUBSCRIPTION_MANAGER_H
#define SUBSCRIPTION_MANAGER_H
/**************************************************/
/******* DO NOT CHANGE the following order ********/
/**************************************************/
/* Logging related header files are required to be included in the following order:
* 1. Include the header file "logging_levels.h".
* 2. Define LIBRARY_LOG_NAME and LIBRARY_LOG_LEVEL.
* 3. Include the header file "logging_stack.h".
*/
/* Include header that defines log levels. */
#include "logging_levels.h"
/* Logging configuration for the Subscription Manager module. */
#ifndef LIBRARY_LOG_NAME
#define LIBRARY_LOG_NAME "Subscription Manager"
#endif
#ifndef LIBRARY_LOG_LEVEL
#define LIBRARY_LOG_LEVEL LOG_ERROR
#endif
#include "logging_stack.h"
/* Demo config include. */
#include "demo_config.h"
/* core MQTT include. */
#include "core_mqtt.h"
/**
* @brief Maximum number of subscriptions maintained by the subscription manager
* simultaneously in a list.
*/
#ifndef SUBSCRIPTION_MANAGER_MAX_SUBSCRIPTIONS
#define SUBSCRIPTION_MANAGER_MAX_SUBSCRIPTIONS 10U
#endif
/**
* @brief Callback function called when receiving a publish.
*
* @param[in] pvIncomingPublishCallbackContext The incoming publish callback context.
* @param[in] pxPublishInfo Deserialized publish information.
*/
typedef void (* IncomingPubCallback_t )( void * pvIncomingPublishCallbackContext,
MQTTPublishInfo_t * pxPublishInfo );
/**
* @brief An element in the list of subscriptions.
*
* This subscription manager implementation expects that the array of the
* subscription elements used for storing subscriptions to be initialized to 0.
*
* @note This implementation allows multiple tasks to subscribe to the same topic.
* In this case, another element is added to the subscription list, differing
* in the intended publish callback. Also note that the topic filters are not
* copied in the subscription manager and hence the topic filter strings need to
* stay in scope until unsubscribed.
*/
typedef struct subscriptionElement
{
IncomingPubCallback_t pxIncomingPublishCallback;
void * pvIncomingPublishCallbackContext;
uint16_t usFilterStringLength;
const char * pcSubscriptionFilterString;
} SubscriptionElement_t;
/**
* @brief Add a subscription to the subscription list.
*
* @note Multiple tasks can be subscribed to the same topic with different
* context-callback pairs. However, a single context-callback pair may only be
* associated to the same topic filter once.
*
* @param[in] pxSubscriptionList The pointer to the subscription list array.
* @param[in] pcTopicFilterString Topic filter string of subscription.
* @param[in] usTopicFilterLength Length of topic filter string.
* @param[in] pxIncomingPublishCallback Callback function for the subscription.
* @param[in] pvIncomingPublishCallbackContext Context for the subscription callback.
*
* @return `true` if subscription added or exists, `false` if insufficient memory.
*/
bool addSubscription( SubscriptionElement_t * pxSubscriptionList,
const char * pcTopicFilterString,
uint16_t usTopicFilterLength,
IncomingPubCallback_t pxIncomingPublishCallback,
void * pvIncomingPublishCallbackContext );
/**
* @brief Remove a subscription from the subscription list.
*
* @note If the topic filter exists multiple times in the subscription list,
* then every instance of the subscription will be removed.
*
* @param[in] pxSubscriptionList The pointer to the subscription list array.
* @param[in] pcTopicFilterString Topic filter of subscription.
* @param[in] usTopicFilterLength Length of topic filter.
*/
void removeSubscription( SubscriptionElement_t * pxSubscriptionList,
const char * pcTopicFilterString,
uint16_t usTopicFilterLength );
/**
* @brief Handle incoming publishes by invoking the callbacks registered
* for the incoming publish's topic filter.
*
* @param[in] pxSubscriptionList The pointer to the subscription list array.
* @param[in] pxPublishInfo Info of incoming publish.
*
* @return `true` if an application callback could be invoked;
* `false` otherwise.
*/
bool handleIncomingPublishes( SubscriptionElement_t * pxSubscriptionList,
MQTTPublishInfo_t * pxPublishInfo );
#endif /* SUBSCRIPTION_MANAGER_H */
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