Implemented a simple caching mechanism in RAM.

Feed the watchdog so it doesn't die while iterating over cards.

Author: jasiek

src/ACNodeClient.ino

@@ -32,7 +32,7 @@ ACNodeClient
 #include "card.h"
 #include "sdcache.h"
 #include "eepromcache.h"
-#include "nocache.h"
+#include "ramcache.h"
 #include "doorbot.h"
 #include "doorbot_ac.h"
 
@@ -109,8 +109,8 @@ void setup() {
       Serial.println("Using the SD Card to cache cards");
     } else {
       Serial.println("SD card could not be accessed");
-      Serial.println("Please fix the SD card and try again. Cache is disabled until reboot.");
-      cache = new NoCache();
+      Serial.println("Please fix the SD card and try again. Caching cards in RAM for now.");
+      cache = new RAMCache();
     }
   } else {
       Serial.println("Using the eeprom to cache cards");

src/cache.cpp

@@ -21,6 +21,7 @@ void Cache::fill(const int count) {
 }
 
 void list_callback(Card c) {
+  wdog.feed();
   c.dump();
 }
 
@@ -30,4 +31,3 @@ void Cache::list(void) {
   Serial.print(count);
   Serial.println(" users");
 }
-

src/ramcache.cpp

@@ -1,5 +1,8 @@
 #include "ramcache.h"
 #include "network.h"
+#include "watchdog.h"
+
+extern Watchdog wdog;
 
 CacheEntry::CacheEntry() :
   expires_at(0),
@@ -26,6 +29,8 @@ void CacheEntry::expire() {
 }
 
 void RAMCache::begin() {
+  Serial.println("RAM Cache TTL: " + String(CACHE_TTL));
+  Serial.println("RAM Cache memory: " + String(sizeof(CacheEntry) * CACHE_CAPACITY));
   purge();
 }
 
@@ -88,6 +93,7 @@ void RAMCache::verify() {
   for (int i = 0; i < CACHE_CAPACITY; i++) {
     CacheEntry *entry = &entries[i];
     if (!entry->expired(now)) {
+      wdog.feed();
       int status = networking::querycard(entry->card);
       switch (status) {
         case 2:

src/ramcache.h

@@ -0,0 +1,33 @@
+#ifndef _RAMCACHE_H
+#define _RAMCACHE_H
+
+#include "cache.h"
+#include "card.h"
+
+#define CACHE_TTL 8 * 3600 * 1000 // eight hours
+#define CACHE_CAPACITY 1500
+
+class CacheEntry {
+public:
+  CacheEntry();
+  CacheEntry(Card c);
+  bool expired(unsigned long now);
+  void expire();
+  void touch(unsigned long now);
+  unsigned long expires_at;
+  Card card;
+};
+
+class RAMCache : public Cache {
+public:
+  virtual void begin();
+  virtual Card get(Card u);
+  virtual void set(const Card u);
+  virtual void purge(void);
+  virtual int each(void( *callback)(Card c));
+  virtual void verify(void);
+private:
+  CacheEntry entries[CACHE_CAPACITY];
+};
+
+#endif