Added ObjectPool

DccMQTT.cpp

@@ -37,16 +37,20 @@
 #include <DCCTimer.h>
 #include <DccMQTT.h>
 #include <Queue.h>
+#include <ObjectPool.h>
 
 //---------
 // Variables
 //---------
 
+DccMQTT DccMQTT::singleton;
+auto mqtt = DccMQTT::get();
+
 char topicName[MAXTBUF];
 char topicMessage[MAXTMSG];
 // char keyword[MAX_KEYWORD_LENGTH];
 
-DccMQTT DccMQTT::singleton;
+
 
 /**
  * @brief Copies an byte array to a hex representation as string; used for generating the unique Arduino ID
@@ -73,8 +77,21 @@ void mqttCallback(char *topic, byte *payload, unsigned int length)
   topicName[0] = '\0';
   topicMessage[0] = '\0';
   strcpy(topicName, topic);
-  strlcpy(topicMessage, (char *)payload, length + 1);
-  DIAG(F("MQTT Message arrived [%s]: [%s]"), topicName, topicMessage);
+
+  auto pool = mqtt->getPool();
+  auto q = mqtt->getIncomming();
+
+  csmsg_t tm;
+  strlcpy(tm.cmd, (char *)payload, length + 1);
+  // Add the recieved command to the pool
+  int idx = pool->setItem(tm);
+  if ( idx == -1) {
+    DIAG(F("MQTT Command pool full. Could not handle recieved command."));
+    return;
+  }
+  // Add the index of the pool item to the incomming queue 
+  q->push(idx);
+  DIAG(F("MQTT Message arrived [%s]: [%s]"), topicName, tm.cmd);
 }
 
 /**

DccMQTT.h

@@ -14,6 +14,7 @@
 #include <Queue.h>
 #include <Ethernet.h>
 #include <Dns.h>
+#include <ObjectPool.h>
 
 #define MAXPAYLOAD 64
 #define MAXDOMAINLENGTH 32
@@ -78,10 +79,9 @@ struct MQTTBroker
     };
 };
 
-struct DccMQTTMsg
-{
-    char payload[MAXPAYLOAD];
-};
+typedef struct csmsg_t { 
+	char cmd[MAXPAYLOAD]; 
+} csmsg_t; 
 
 enum DccMQTTState
 {
@@ -107,8 +107,9 @@ private:
     PubSubClient    mqttClient;     // PubSub Endpoint for data exchange
     MQTTBroker      *broker;        // Broker configuration object as set in config.h
  
-    Queue<DccMQTTMsg> in;
-    Queue<DccMQTTMsg> out;
+    ObjectPool<csmsg_t,MAXPOOLSIZE> pool;
+    Queue<int> in;
+    Queue<int> out;
 
     char clientID[(CLIENTIDSIZE*2)+1];
 
@@ -124,6 +125,11 @@ public:
     bool isConnected() { return mqState == CONNECTED; };
     void setState(DccMQTTState s) { mqState = s; };
 
+    ObjectPool<csmsg_t,MAXPOOLSIZE> *getPool() { return &pool; };
+    Queue<int> *getIncomming() { return &in; };
+    Queue<int> *getOutgoing() { return &out; };
+
+
     void setup(); // called at setup in the main ino file
     void loop();
 

ObjectPool.h

@@ -0,0 +1,91 @@
+#ifndef _ObjectPool_h_
+#define _ObjectPool_h_
+
+#include <DIAG.h>
+
+#define MAXPOOLSIZE 32
+
+template <typename T, int length>
+class ObjectPool
+{
+
+    // just make sure that we don't create a pool eating up all memory @compiletime
+    static_assert(length <= MAXPOOLSIZE); 
+
+    struct item
+    {
+        T i;
+        bool free = true; // boolean 1 free i.e. i can be reused; 0 occupied
+    };
+
+private:
+    item p[length];          // MAXPOOLSIZE items of struct item
+    const int size = length; // size of the pool
+
+    int findFreeIdx()
+    { // find the first free index or return -1 if there is none
+        for (int i = 0; i < length; i++)
+        {
+            if (p[i].free)
+            {
+                return i;
+            }
+        }
+        return -1; // if we are here there is no free slot available
+    }
+
+public:
+    int setItem(T i)
+    { // add an item to the pool at a free slot
+        int idx = findFreeIdx();
+        if (idx != -1)
+        {
+            p[idx].i = i;
+            p[idx].free = false;
+        }
+        return idx;
+    }
+
+    /**
+     * @brief returns the slot for an object to the pool i.e. frees the slot for reuse of the data member and
+     * clears out the memory
+     * 
+     * @param idx 
+     * @return true  if the return is ok
+     * @return false otherwise
+     */
+    bool returnItem(int idx)
+    { // clear item at pool index idx
+        if (idx > size)
+        { // can't return an item outside of the pool size; returns false;
+            return false;
+        }
+        memset(&p[idx].i, 0, sizeof(T)); // clear out the memory but keep the allocation for reuse
+        p[idx].free = true;
+        return true; // set the free flag
+    }
+
+    /**
+     * @brief Obtain a pool item
+     * @note This should only be used for debugging. 
+     * It allows to change actually the content of the pool item where this should only be allowed for the setItem method.
+     * @param idx Index of the pool item to retrieve 
+     * @param state State of the pool item ( 1 available, 0 occupied)
+     * @return T* returns the pointer to the pool item
+     */
+    T *getItem(int idx, bool *state)
+    {
+        *state = p[idx].free;
+        return &p[idx].i;
+    }
+
+    int getSize()
+    {
+        return size;
+    }
+
+    ObjectPool() = default;
+    ~ObjectPool() = default;
+};
+
+#endif