Add enableCache() and flushCache().

cwUi.cpp

@@ -97,6 +97,15 @@ namespace cw
       unsigned        sessN;
       unsigned        sessAllocN;
 
+      
+      bool     msgCacheEnableFl;
+      unsigned msgCacheSessId;
+      char*    msgCache;
+      unsigned msgCacheAllocN;
+      unsigned msgCacheDataN;
+      unsigned msgCacheN;
+      unsigned msgCacheMsgN;
+
     } ui_t;
 
     ui_t* _handleToPtr( handle_t h )
@@ -317,28 +326,100 @@ namespace cw
       return nullptr;
     }
 
-    rc_t _websockSend( ui_t* p, unsigned wsSessId, const char* msg )
+    
+    rc_t _cache_flush( ui_t* p )
     {
       rc_t rc = kOkRC;
 
-      //return websock::send( websockSrv::websockHandle( p->wssH ), kUiProtocolId, wsSessId, msg, strlen(msg) );
-      if( p->sendCbFunc != nullptr )
+      if( p->msgCacheMsgN > 0 )
       {        
-        unsigned msgByteN = msg==nullptr ? 0 : strlen(msg);
+        assert( p->msgCacheN <= p->msgCacheDataN );
+        p->msgCache[ p->msgCacheN+0 ] = ']';
+        p->msgCache[ p->msgCacheN+1 ] = '}';
+        p->msgCache[ p->msgCacheN+2 ] = 0;
               
-        if( wsSessId != kInvalidId )
-          rc = p->sendCbFunc( p->sendCbArg, wsSessId, msg, msgByteN );
-        else
-        {
-          for(unsigned i=0; i<p->sessN; ++i)
-            rc = p->sendCbFunc( p->sendCbArg, p->sessA[i], msg, msgByteN );
+        rc = p->sendCbFunc( p->sendCbArg, p->msgCacheSessId, p->msgCache, strlen(p->msgCache) );
+
+        p->msgCacheN      = snprintf(p->msgCache,p->msgCacheAllocN,"{\"op\":\"cache\", \"array\": [");     
+        p->msgCacheSessId = kInvalidId;
+        p->msgCacheMsgN   = 0;
 
-        }
       }
       
       return rc;
     }
 
+    rc_t _cache_send( ui_t* p, unsigned wsSessId, const char* msg, unsigned msgByteN )
+    {
+      rc_t rc = kOkRC;
+
+      unsigned msgByteCommaN = msgByteN + 1;
+
+      // if the cache buffer has not yet been allocated
+      if( p->msgCache == nullptr && p->msgCacheAllocN>0 )
+      {
+        p->msgCacheDataN  = p->msgCacheAllocN - 3; // "]}/0" three char's must be reserved to terminate the cache message (See _cache_flush().)
+        p->msgCache       = mem::allocZ<char>( p->msgCacheAllocN );
+        p->msgCacheSessId = kInvalidId;
+        p->msgCacheN      = snprintf(p->msgCache,p->msgCacheDataN,"{\"op\":\"cache\", \"array\": [");
+        p->msgCacheMsgN   = 0;
+      }
+      
+      if( wsSessId != p->msgCacheSessId ||  p->msgCacheN + msgByteCommaN > p->msgCacheDataN  || msgByteN > p->msgCacheDataN )        
+        rc = _cache_flush(p);
+
+      if( msgByteN > p->msgCacheDataN )
+        rc = p->sendCbFunc( p->sendCbArg, wsSessId, msg, msgByteN );
+      else
+      {
+        assert( p->msgCacheN + msgByteCommaN <= p->msgCacheDataN );
+
+        // if this isn't the first msg is the buffer then prepend a ','
+        if( p->msgCacheMsgN != 0 )
+          strncat(p->msgCache,",",2);
+        else
+          msgByteCommaN -= 1;  // otherwise the msgByteCommaN is the same as msgByteN
+        
+        strncat(p->msgCache,msg,msgByteN);
+        
+        p->msgCacheN += msgByteCommaN;
+        p->msgCacheSessId = wsSessId;
+        p->msgCacheMsgN += 1;
+      }
+      
+      return rc;
+    }
+
+    rc_t _send_or_cache( ui_t* p, unsigned sessId, const char* msg, unsigned msgByteCnt )
+    {
+      rc_t rc = kOkRC;
+      if( p->msgCacheEnableFl )
+        rc = _cache_send( p, sessId, msg, msgByteCnt );
+      else
+        rc =  p->sendCbFunc( p->sendCbArg, sessId, msg, msgByteCnt );
+
+      return rc;
+    }
+    
+    rc_t _websockSend( ui_t* p, unsigned wsSessId, const char* msg )
+    {
+      rc_t rc = kOkRC;
+      
+      if( p->sendCbFunc != nullptr )
+      {
+        unsigned msgByteN = msg==nullptr ? 0 : strlen(msg);
+
+        if( wsSessId != kInvalidId )
+          rc = _send_or_cache( p, wsSessId, msg, msgByteN );
+        else
+        {
+          for(unsigned i=0; i<p->sessN; ++i)
+            rc = _send_or_cache( p, p->sessA[i], msg, msgByteN );          
+        }        
+      }
+      
+      return rc;
+    }
 
     // terminating condition for format_attributes()
     void _create_attributes( ele_t* e )
@@ -1191,6 +1272,7 @@ cw::rc_t cw::ui::create(
   p->recvBufIdx = 0;
   p->recvShiftN = 0;
   p->uiRsrc     = uiRsrc->duplicate();
+  p->msgCacheSessId = kInvalidId;
   
   // create the root element
   if((ele = _createBaseEle(p, nullptr, kRootAppId, kInvalidId, "uiDivId" )) == nullptr || ele->uuId != kRootUuId )
@@ -1243,6 +1325,24 @@ cw::rc_t cw::ui::destroy( handle_t& h )
   return rc;
 }
 
+cw::rc_t cw::ui::enableCache( handle_t h, unsigned cacheByteCnt )
+{
+  ui_t* p = _handleToPtr(h);
+  p->msgCacheEnableFl = true;
+  p->msgCacheAllocN = cacheByteCnt;
+  return kOkRC;
+}
+
+cw::rc_t cw::ui::flushCache( handle_t h )
+{
+  rc_t rc = kOkRC;
+  ui_t* p = _handleToPtr(h);
+
+  if( p->msgCacheEnableFl && p->msgCache != nullptr )
+    rc =_cache_flush(p);
+  return rc;
+ }
+
 
 unsigned        cw::ui::sessionIdCount(handle_t h)
 {
@@ -1657,7 +1757,6 @@ cw::rc_t cw::ui::createLog(   handle_t h, unsigned& uuIdRef, unsigned parentUuId
 cw::rc_t cw::ui::createList( handle_t h, unsigned& uuIdRef, unsigned parentUuId, const char* eleName, unsigned appId, unsigned chanId, const char* clas, const char* title )
 { return _createOneEle( _handleToPtr(h), uuIdRef, "list", kInvalidId, parentUuId, eleName, appId, chanId, clas, title);  }
 
-
 cw::rc_t cw::ui::setNumbRange( handle_t h, unsigned uuId, double minValue, double maxValue, double stepValue, unsigned decPl, double value )
 {
   rc_t rc = kOkRC;

cwUi.h

@@ -32,6 +32,9 @@ namespace cw
     
     rc_t destroy( handle_t& h );
 
+    rc_t enableCache( handle_t h, unsigned cacheByteCnt=4096 );
+    rc_t flushCache( handle_t h );
+    
     unsigned        sessionIdCount(handle_t h);  // Count of connected remote UI's
     const unsigned* sessionIdArray(handle_t h);  // Array of 'sessionIdCount()' remote UI id's