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Replace exponential_backoff with submodule to FreeRTOS/backoffAlgorithm (#419)

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A new repository, FreeRTOS/backoffAlgorithm, has been created for hosting the library for backoff calculation. This repo replaces the FreeRTOS-Plus/Source/Utilities/exponential_backoff with the submodule to the new repository, and updates all the demos that use retry logic to use the backoffAlgorithm API
This commit is contained in:
Archit Aggarwal
2020-11-24 14:54:31 -08:00
committed by GitHub
parent 5ba1e4cf95
commit 036ec83b65
33 changed files with 699 additions and 554 deletions
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81
FreeRTOS-Plus/Demo/AWS/Mqtt_Demo_Helpers/mqtt_demo_helpers.c
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@ -51,7 +51,7 @@
#include "core_mqtt.h"
/* Exponential backoff retry include. */
#include "exponential_backoff.h"
#include "backoff_algorithm.h"
/* Transport interface implementation include header for TLS. */
#include "using_mbedtls.h"
@ -84,6 +84,23 @@
/*-----------------------------------------------------------*/
/**
* @brief The maximum number of retries for network operation with server.
*/
#define RETRY_MAX_ATTEMPTS ( 5U )
/**
* @brief The maximum back-off delay (in milliseconds) for retrying failed operation
* with server.
*/
#define RETRY_MAX_BACKOFF_DELAY_MS ( 5000U )
/**
* @brief The base back-off delay (in milliseconds) to use for network operation retry
* attempts.
*/
#define RETRY_BACKOFF_BASE_MS ( 500U )
/**
* @brief Timeout for receiving CONNACK packet in milliseconds.
*/
@ -220,6 +237,22 @@ static PublishPackets_t outgoingPublishPackets[ MAX_OUTGOING_PUBLISHES ] = { 0 }
/*-----------------------------------------------------------*/
/**
* @brief A wrapper to the "uxRand()" random number generator so that it
* can be passed to the backoffAlgorithm library for retry logic.
*
* This function implements the #BackoffAlgorithm_RNG_T type interface
* in the backoffAlgorithm library API.
*
* @note The "uxRand" function represents a pseudo random number generator.
* However, it is recommended to use a True Randon Number Generator (TRNG)
* for generating unique device-specific random values to avoid possibility
* of network collisions from multiple devices retrying network operations.
*
* @return The generated randon number. This function ALWAYS succeeds.
*/
static int32_t prvGenerateRandomNumber();
/**
* @brief Connect to MQTT broker with reconnection retries.
*
@ -285,12 +318,20 @@ static uint32_t prvGetTimeMs( void );
/*-----------------------------------------------------------*/
static int32_t prvGenerateRandomNumber()
{
return( uxRand() & INT32_MAX );
}
/*-----------------------------------------------------------*/
static TlsTransportStatus_t prvConnectToServerWithBackoffRetries( NetworkContext_t * pxNetworkContext )
{
TlsTransportStatus_t xNetworkStatus = TLS_TRANSPORT_SUCCESS;
RetryUtilsStatus_t xRetryUtilsStatus = RetryUtilsSuccess;
RetryUtilsParams_t xReconnectParams = { 0 };
BackoffAlgorithmStatus_t xBackoffAlgStatus = BackoffAlgorithmSuccess;
BackoffAlgorithmContext_t xReconnectParams = { 0 };
NetworkCredentials_t xNetworkCredentials = { 0 };
uint16_t usNextRetryBackOff = 0U;
/* ALPN protocols must be a NULL-terminated list of strings. Therefore,
* the first entry will contain the actual ALPN protocol string while the
@ -318,9 +359,15 @@ static TlsTransportStatus_t prvConnectToServerWithBackoffRetries( NetworkContext
#endif
xNetworkCredentials.pAlpnProtos = pcAlpnProtocols;
/* Initialize reconnect attempts and interval. */
RetryUtils_ParamsReset( &xReconnectParams );
xReconnectParams.maxRetryAttempts = MAX_RETRY_ATTEMPTS;
/* Initialize reconnect attempts and interval.
* Note: This utility uses a pseudo random number generator for use with the backoff
* algorithm. However, it is recommended to use a True Random Number generator to
* avoid possibility of collisions between multiple devices retrying connection. */
BackoffAlgorithm_InitializeParams( &xReconnectParams,
RETRY_BACKOFF_BASE_MS,
RETRY_MAX_BACKOFF_DELAY_MS,
RETRY_MAX_ATTEMPTS,
prvGenerateRandomNumber );
/* Attempt to connect to MQTT broker. If connection fails, retry after
* a timeout. Timeout value will exponentially increase until maximum
@ -343,16 +390,22 @@ static TlsTransportStatus_t prvConnectToServerWithBackoffRetries( NetworkContext
if( xNetworkStatus != TLS_TRANSPORT_SUCCESS )
{
LogWarn( ( "Connection to the broker failed. Retrying connection with backoff and jitter." ) );
xRetryUtilsStatus = RetryUtils_BackoffAndSleep( &xReconnectParams );
}
/* Get back-off value (in milliseconds) for the next connection retry. */
xBackoffAlgStatus = BackoffAlgorithm_GetNextBackoff( &xReconnectParams, &usNextRetryBackOff );
configASSERT( xBackoffAlgStatus != BackoffAlgorithmRngFailure );
if( xRetryUtilsStatus == RetryUtilsRetriesExhausted )
{
LogError( ( "Connection to the broker failed, all attempts exhausted." ) );
xNetworkStatus = TLS_TRANSPORT_CONNECT_FAILURE;
if( xBackoffAlgStatus == BackoffAlgorithmRetriesExhausted )
{
LogError( ( "Connection to the broker failed, all attempts exhausted." ) );
}
else if( xBackoffAlgStatus == BackoffAlgorithmSuccess )
{
LogWarn( ( "Connection to the broker failed. "
"Retrying connection with backoff and jitter." ) );
vTaskDelay( pdMS_TO_TICKS( usNextRetryBackOff ) );
}
}
} while( ( xNetworkStatus != TLS_TRANSPORT_SUCCESS ) && ( xRetryUtilsStatus == RetryUtilsSuccess ) );
} while( ( xNetworkStatus != TLS_TRANSPORT_SUCCESS ) && ( xBackoffAlgStatus == BackoffAlgorithmSuccess ) );
return xNetworkStatus;
}