Add memory management for clients

Author: sebromero

src/ArduinoCellular.cpp

@@ -1,7 +1,6 @@
 
 
 #include "ArduinoCellular.h"
-#include "ManagedTinyGsmClient.h"
 
 #if defined(ARDUINO_ARCH_MBED)
   #include "Watchdog.h"
@@ -17,6 +16,10 @@ unsigned long ArduinoCellular::getTime() {
 ArduinoCellular::ArduinoCellular() {
 }
 
+ArduinoCellular::~ArduinoCellular() {
+    cleanup();
+}
+
 void ArduinoCellular::begin() {
     modem.init();
 
@@ -177,14 +180,34 @@ HttpClient ArduinoCellular::getHTTPClient(const char * server, const int port){
 
 #if defined(ARDUINO_CELLULAR_BEARSSL)
 HttpClient ArduinoCellular::getHTTPSClient(const char * server, const int port){
-    return HttpClient(* new BearSSLClient(* new ManagedTinyGsmClient(modem)), server, port);
+    auto gsmClient = std::make_unique<ManagedTinyGsmClient>(modem);
+    auto sslClient = std::make_unique<BearSSLClient>(*gsmClient);
+    auto& sslRef = *sslClient;
+    
+    managedGsmClients.push_back(std::move(gsmClient));
+    managedSslClients.push_back(std::move(sslClient));
+    return HttpClient(sslRef, server, port);
 }
 
 BearSSLClient ArduinoCellular::getSecureNetworkClient(){
     return BearSSLClient(* new ManagedTinyGsmClient(modem));
 }
 #endif
 
+void ArduinoCellular::cleanup() {
+    /*
+    It's necessary to to manage the lifetime of the clients created by the library
+    because the HttpClient and also BearSSLClient classes expect callers to manage the lifetime of the clients.
+    For convenience, the library provides factory functions that allocate these objects on behalf of the caller.
+     */
+    managedSslClients.clear();  // Destroys BearSSLClient instances
+    managedGsmClients.clear();  // Destroys ManagedTinyGsmClient instances
+}
+
+size_t ArduinoCellular::getManagedClientCount() const {
+    return managedSslClients.size();
+}
+
 bool ArduinoCellular::isConnectedToOperator(){
     return modem.isNetworkConnected();
 }

src/ArduinoCellular.h

@@ -16,6 +16,7 @@
 
 #include <Arduino.h>
 #include <vector>
+#include <memory>
 
 #if defined __has_include
   #if !__has_include (<ArduinoIoTCloud.h>)
@@ -30,6 +31,7 @@
 
 #include <ModemInterface.h>
 #include <TimeUtils.h>
+#include "ManagedTinyGsmClient.h"
 
 /**
  * @enum ModemModel
@@ -100,6 +102,36 @@ class ArduinoCellular {
          */
         ArduinoCellular();
 
+        /**
+         * @brief Destructor for the ArduinoCellular class.
+         * Cleans up any resources used by the class.
+         */
+        ~ArduinoCellular();
+
+        /**
+         * @brief Deleted copy constructor and assignment operator to prevent copying.
+         * unique_ptr is used to manage the lifetime of the clients but they cannot be copied.
+         */
+        ArduinoCellular(const ArduinoCellular&) = delete;
+
+        /**
+         * @brief Deleted assignment operator to prevent copying.
+         * unique_ptr is used to manage the lifetime of the clients but they cannot be copied.
+         */
+        ArduinoCellular& operator=(const ArduinoCellular&) = delete;
+
+        /**
+         * @brief Move constructor for the ArduinoCellular class.
+         * Allows moving the instance to another instance.
+         */
+        ArduinoCellular(ArduinoCellular&&) = default;
+
+        /**
+         * @brief Move assignment operator for the ArduinoCellular class.
+         * Allows moving the instance to another instance.
+         */
+        ArduinoCellular& operator=(ArduinoCellular&&) = default;
+
         /**
          * @brief Initializes the modem.
          * This function must be called before using any other functions in the library.
@@ -238,6 +270,7 @@ class ArduinoCellular {
         /**
          * @brief Gets a HTTP client for the specified server and port.
          * The maximum number of HTTP clients is limited by the number of sockets available.
+         * Call `cleanup()` to release the resources used by the clients once you are done with them.
          * @param server The server address.
          * @param port The server port.
          * @return The HTTP client.
@@ -247,12 +280,26 @@ class ArduinoCellular {
         /**
          * @brief Gets a HTTPS client for the specified server and port.
          * The maximum number of HTTP clients is limited by the number of sockets available.
+         * Call `cleanup()` to release the resources used by the clients once you are done with them.
          * @param server The server address.
          * @param port The server port.
          * @return The HTTPS client.
          */
         HttpClient getHTTPSClient(const char * server, const int port);
 
+        /**
+         * @brief Cleans up the clients and releases the resources used by them.
+         * It's necessary to call this function to free up the memory used by the client
+         * objects that are created by the library internally.
+         */
+        void cleanup();
+
+        /**
+         * @brief Gets the number of managed clients.
+         * The clients are managed in the sense of memory management.
+         */
+        size_t getManagedClientCount() const;
+
         /**
          * @brief Gets the local IP address.
          * @return The local IP address.
@@ -282,6 +329,10 @@ class ArduinoCellular {
         SimStatus getSimStatus();
 
     private:
+        // Each instance manages its own connections
+        std::vector<std::unique_ptr<ManagedTinyGsmClient>> managedGsmClients;
+        std::vector<std::unique_ptr<BearSSLClient>> managedSslClients;
+
         bool connectToGPRS(const char * apn, const char * gprsUser, const char * gprsPass);