Improved CRC32Map checking in several ways:

- servers now compute the map in a separate thread
- CRC32Maps are kept in cache for 30 mins
- CRC32Maps requests cannot be used to overflood a server anymore since their number is limited.
- Transfer modules now send keep alive packets to maintain tunnels when asking for a CRC32Map



git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@4661 b45a01b8-16f6-495d-af2f-9b41ad6348cc

libretroshare/src/ft/ftfileprovider.cc

@@ -318,15 +318,4 @@ int ftFileProvider::initializeFileAttrs()
 	return 1;
 }
 
-bool ftFileProvider::getCRC32Map(CRC32Map& crc_map)
-{
-	if(!initializeFileAttrs())
-	{
-		std::cerr << "ftFileProvider::getCRC32Map(...): ERROR: can't initialize file !" << std::endl ;
-		return false ;
-	}
-
-	std::cerr << "ftFileProvider::getClientMap(): computing CRC32 map for file " << file_name << " (" << hash << ")" << std::endl ;
-	return RsDirUtil::crc32File(fd,mSize,ChunkMap::CHUNKMAP_FIXED_CHUNK_SIZE,crc_map) ;
-}