checked in first bits of code for cache service data optimisation,

distrib can build grps xml document
added pugixml src code into utilities

pls see design document:
http://retroshare.sourceforge.net/wiki/index.php/Documentation:design_services_histories

git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@4076 b45a01b8-16f6-495d-af2f-9b41ad6348cc

libretroshare/src/dbase/cachestrapper.cc

@@ -259,6 +259,21 @@ bool	CacheStore::getStoredCache(CacheData &data)
 	return ok;
 }
 
+bool CacheStore::cached(const std::string cacheId)
+{
+
+	return false;
+}
+
+void CacheStore::updateCacheDocument(pugi::xml_document& cacheDoc)
+{
+	return;
+}
+
+void CacheStore::updateCacheTable()
+{
+	return;
+}
 
 bool	CacheStore::locked_getStoredCache(CacheData &data)
 {

libretroshare/src/dbase/cachestrapper.h

@@ -27,6 +27,7 @@
 #include "pqi/p3cfgmgr.h"
 #include "pqi/pqimonitor.h"
 #include "util/rsthreads.h"
+#include "util/pugixml.h"
 
 #include <list>
 #include <map>
@@ -217,6 +218,7 @@ class CacheSource
 
 /*!
  * Base Class for data cache. eg. FileCache/Store.
+ * This is best used to deal with external caches from other peers
  * @see p3Distrib. pqiMonitor
  */
 class CacheStore
@@ -313,7 +315,33 @@ class CacheStore
 		 */
 		bool    locked_getStoredCache(CacheData &data);
 
+
+		//////////////// Cache Optimisation //////////////////
+
+		/**
+		 *@param id the key for determing whether this data has been cached or not
+		 *@return true if data referenced by key has been cached false otherwise
+		 */
+		bool cached(const std::string cacheId);
+
+		/**
+		 * TODO: will be abstract
+		 * The deriving class should return a document which accurately reflects its data
+		 * structure
+		 * @param cacheDoc document reflecting derving class's cache data structure
+		 */
+		virtual void updateCacheDocument(pugi::xml_document& cacheDoc);
+
+
+
+
+		//////////////// Cache Optimisation //////////////////
 		private:
+		/**
+		 * This updates the cache table with information from the xml document
+		 *
+		 */
+		void updateCacheTable();
 
 		uint16_t cacheType;    /* for checking */
 		bool     multiCache;   /* do we care about subid's */
@@ -324,9 +352,16 @@ class CacheStore
 		std::string cacheDir;
 
 		mutable RsMutex cMutex;
-
 		std::map<RsPeerId, CacheSet> caches;
 
+		////////////// cache optimisation ////////////////
+
+		/// whether to run in cache optimisation mode
+		bool cacheOptMode;
+
+		/// stores whether given instance of cache data has been loaded already or not
+		std::map<std::string, bool>  cacheTable;
+
 };