[fluksod] join the fill and truncate operations in a single method

mote/v2/openwrt/package/flukso/luasrc/flukso/data.lua

@@ -90,29 +90,28 @@ function filter(M, span, offset)
 	end
 end
 
-function truncate(M, cutoff)
+function polish(M, cutoff)
-	for sensor, T in pairs(M) do
+	local now = os.time()
-		local H = timestamps(T)
+
-
-		for i = H[1], os.time() - cutoff do
-			T[i] = nil
-		end
-	end
-end
-
-function fill(M)
 	for sensor, T in pairs(M) do
 		local H = timestamps(T)
 
+		-- fill up the holes first
 		for i = H[#H]-1, H[1]+1, -1 do
 			if T[i] == nil or T[i] == '"nan"' then
 				T[i] = T[i+1]
 			end
 		end
 
-		for i = H[#H]+1, os.time() do
+		-- make sure the tail stretches up to 'now'
+		for i = H[#H]+1, now do
 			T[i] = '"nan"'
 		end
+
+		-- truncate the head
+		for i = H[1], now - cutoff do
+			T[i] = nil
+		end
 	end
 end
 
@@ -127,7 +126,7 @@ function json_encode(M)
 			SB[#SB+1] = '[' .. timestamp .. ',' .. T[timestamp]  .. '],'
 		end
 
-		SB[#SB] = SB[#SB]:sub(1, -2) -- remove the trialing comma from the last entry
+		SB[#SB] = SB[#SB]:sub(1, -2) -- remove the trailing comma from the last entry
 		SB[#SB+1] = ']'
 		J[sensor] = table.concat(SB)
 	end

mote/v2/openwrt/package/flukso/luasrc/fluksod.lua

@@ -311,30 +311,20 @@ function lan_buffer(child)
 	end)
 end
 
-function polish(child, cutoff)
+function publish(child)
 	return coroutine.create(function(measurements)
-		while true do
+		nixio.fs.mkdirr(LAN_PUBLISH_PATH)
-			measurements:fill()
-			measurements:truncate(cutoff)
-			coroutine.resume(child, measurements)
-			measurements = coroutine.yield()
-		end
-	end)
-end
 
-function publish(child, dir)
+		for file in nixio.fs.dir(LAN_PUBLISH_PATH) do
-	return coroutine.create(function(measurements)
-		nixio.fs.mkdirr(dir)
-
-		for file in nixio.fs.dir(dir) do
 			nixio.fs.unlink(file)
 		end
 
 		while true do
+			measurements:polish(LAN_POLISH_CUTOFF)
 			local measurements_json = measurements:json_encode()
 
 			for sensor_id, json in pairs(measurements_json) do
-				local file = dir .. '/' .. sensor_id
+				local file = LAN_PUBLISH_PATH .. '/' .. sensor_id
 				
 				nixio.fs.unlink(file)
 				fd = nixio.open(file, O_RDWR_CREAT)
@@ -381,11 +371,9 @@ local wan_chain =
 
 local lan_chain =
 	lan_buffer(
-		polish(
 		publish(
 			debug(nil)
-			, LAN_PUBLISH_PATH)
+		)
-		, LAN_POLISH_CUTOFF)
 	)
 
 local chain = dispatch(wan_chain, lan_chain)