cleanup: use current_memsize instead of counting cache sizes

unireader.lua

@@ -1063,13 +1063,11 @@ function UniReader:cacheClaim(size)
 		return false
 	end
 	-- reduce ttl of each cache
-	local calculated_size = 0
 	for k, _ in pairs(self.cache) do
 		self.cache[k].ttl = self.cache[k].ttl - 1
-		calculated_size = calculated_size + self.cache[k].size
 	end
 	-- free oldest cache until we have free memory
-	while calculated_size + size > self.cache_max_memsize do
+	while self.cache_current_memsize + size > self.cache_max_memsize do
 		local oldest_cache_ttl = self.cache_max_ttl
 		local oldest_cache_key = nil
 		for k, _ in pairs(self.cache) do
@@ -1081,12 +1079,12 @@ function UniReader:cacheClaim(size)
 		-- cache slot is at end of life, so kick it out
 		if oldest_cache_key then
 			Debug("free cache:", oldest_cache_key, "ttl:", self.cache[oldest_cache_key].ttl)
-			calculated_size = calculated_size - self.cache[oldest_cache_key].size
+			self.cache_current_memsize = self.cache_current_memsize - self.cache[oldest_cache_key].size
 			self.cache[oldest_cache_key].bb:free()
 			self.cache[oldest_cache_key] = nil
 		end
 	end
-	self.cache_current_memsize = calculated_size + size
+	self.cache_current_memsize = self.cache_current_memsize + size
 	return true
 end