Serve static pages efficiently. Fix #53 (#118)

* 1st draft to serve static files faster

* Allow serving 5 images in a page

the 6th image cannot be served as the esp does not open more than 5 connections at the same time

* win the prize

* Update comments

Author: HHHartmann

http/cars.lua

@@ -31,6 +31,10 @@ return function (connection, req, args)
          It works with three embedded images of cars, but the server crashes with four. Select the number of cars you want to see below.<br>
          Whoever manages to modify nodemcu-httpserver to load all four images without crashing wins a prize!
       </p>
+      <p>
+         OK I guess I win the prize, as now you can load five cars.<br>
+            Cheers HHHartmann
+      </p>
       <p>
          choose: <a href="?n=1">show one car</a>
          <a href="?n=2">show two cars</a>

httpserver-buffer.lua

@@ -0,0 +1,48 @@
+-- httpserver-buffer
+-- Part of nodemcu-httpserver, provides a buffer that behaves like a connection object
+-- that can handle multiple consecutive send() calls, and buffers small payloads up to 1400 bytes.
+-- This is primarily user to collect the send requests done by the head script.
+-- The owner is responsible to call getBuffer and send its result
+-- Author: Gregor Hartmann
+
+local Buffer = {}
+
+-- parameter is the nodemcu-firmware connection
+function Buffer:new()
+   local newInstance = {}
+   newInstance.size = 0
+   newInstance.data = {}
+
+   -- Returns true if there was any data to be sent.
+   function newInstance:getBuffer()
+      local buffer = table.concat(self.data, "")
+      self.data = {}
+      self.size = 0
+      return buffer
+   end
+
+   function newInstance:getpeer()
+      return "no peer"
+   end
+
+   function newInstance:send(payload)
+      local flushThreshold = 1400
+      if (not payload) then print("nop payload") end
+      local newSize = self.size + payload:len()
+      if newSize >= flushThreshold then
+         print("Buffer is full. Cutting off "..newSize-flushThreshold.." chars")
+         --STEP1: cut out piece from payload to complete threshold bytes in table
+         local pieceSize = flushThreshold - self.size
+         if pieceSize then
+            payload = payload:sub(1, pieceSize)
+         end
+      end
+      table.insert(self.data, payload)
+      self.size = self.size + #payload
+   end
+   
+   return newInstance
+
+end
+
+return Buffer

httpserver-static.lua

@@ -1,27 +1,13 @@
 -- httpserver-static.lua
 -- Part of nodemcu-httpserver, handles sending static files to client.
--- Author: Marcos Kirsch
+-- Author: Gregor Hartmann
 
 return function (connection, req, args)
-   dofile("httpserver-header.lc")(connection, 200, args.ext, args.isGzipped)
-   -- Send file in little chunks
-   local bytesRemaining = file.list()[args.file]
-   -- Chunks larger than 1024 don't work.
-   -- https://github.com/nodemcu/nodemcu-firmware/issues/1075
-   local chunkSize = 1024
-   local fileHandle = file.open(args.file)
-   while bytesRemaining > 0 do
-      local bytesToRead = 0
-      if bytesRemaining > chunkSize then bytesToRead = chunkSize else bytesToRead = bytesRemaining end
-      local chunk = fileHandle:read(bytesToRead)
-      connection:send(chunk)
-      bytesRemaining = bytesRemaining - #chunk
-      --print(args.file .. ": Sent "..#chunk.. " bytes, " .. bytesRemaining .. " to go.")
-      chunk = nil
-      collectgarbage()
-   end
-   -- print("Finished sending: ", args.file)
-   fileHandle:close()
-   fileHandle = nil
-   collectgarbage()
+
+   local buffer = dofile("httpserver-buffer.lc"):new()
+   dofile("httpserver-header.lc")(buffer, req.code or 200, args.ext, args.isGzipped)
+   -- Send header and return fileInfo
+   connection:send(buffer:getBuffer())
+   
+   return { file = args.file, sent = 0}
 end

httpserver.lua

@@ -13,6 +13,7 @@ return function (port)
          -- We do it in a separate thread because we need to send in little chunks and wait for the onSent event
          -- before we can send more, or we risk overflowing the mcu's buffer.
          local connectionThread
+         local fileInfo
 
          local allowStatic = {GET=true, HEAD=true, POST=false, PUT=false, DELETE=false, TRACE=false, OPTIONS=false, CONNECT=false, PATCH=false}
 
@@ -26,6 +27,10 @@ return function (port)
             end
          end
 
+         local function startServingStatic(connection, req, args)
+            fileInfo = dofile("httpserver-static.lc")(connection, req, args)
+         end
+         
          local function startServing(fileServeFunction, connection, req, args)
             connectionThread = coroutine.create(function(fileServeFunction, bufferedConnection, req, args)
                fileServeFunction(bufferedConnection, req, args)
@@ -40,6 +45,7 @@ return function (port)
 
             local BufferedConnectionClass = dofile("httpserver-connection.lc")
             local bufferedConnection = BufferedConnectionClass:new(connection)
+            BufferedConnectionClass = nil
             local status, err = coroutine.resume(connectionThread, fileServeFunction, bufferedConnection, req, args)
             if not status then
                log(connection, "Error: "..err)
@@ -50,7 +56,7 @@ return function (port)
             end
          end
 
-         local function handleRequest(connection, req)
+         local function handleRequest(connection, req, handleError)
             collectgarbage()
             local method = req.method
             local uri = req.uri
@@ -84,7 +90,8 @@ return function (port)
                else
                   if allowStatic[method] then
                      uri.args = {file = uri.file, ext = uri.ext, isGzipped = uri.isGzipped}
-                     fileServeFunction = dofile("httpserver-static.lc")
+                     startServingStatic(connection, req, uri.args)
+                     return
                   else
                      uri.args = {code = 405, errorString = "Method not supported", logFunction = log}
                      fileServeFunction = dofile("httpserver-error.lc")
@@ -95,7 +102,7 @@ return function (port)
          end
 
          local function onReceive(connection, payload)
-            collectgarbage()
+--            collectgarbage()
             local conf = dofile("httpserver-conf.lc")
             local auth
             local user = "Anonymous"
@@ -162,6 +169,27 @@ return function (port)
                   connectionThread = nil
                   collectgarbage()
                end
+            elseif fileInfo then
+               local fileSize = file.list()[fileInfo.file]
+               -- Chunks larger than 1024 don't work.
+               -- https://github.com/nodemcu/nodemcu-firmware/issues/1075
+               local chunkSize = 512
+               local fileHandle = file.open(fileInfo.file)
+               if fileSize > fileInfo.sent then
+                  fileHandle:seek("set", fileInfo.sent)
+                  local chunk = fileHandle:read(chunkSize)
+                  fileHandle:close()
+                  fileHandle = nil
+                  fileInfo.sent = fileInfo.sent + #chunk
+                  connection:send(chunk)
+                  -- print(fileInfo.file .. ": Sent "..#chunk.. " bytes, " .. fileSize - fileInfo.sent .. " to go.")
+                  chunk = nil
+               else
+                  log(connection, "closing connetion", "Finished sending: "..fileInfo.file)
+                  connection:close()
+                  fileInfo = nil
+               end
+               collectgarbage()
             end
          end
 
@@ -172,6 +200,10 @@ return function (port)
                connectionThread = nil
                collectgarbage()
             end
+            if fileInfo then
+               fileInfo = nil
+               collectgarbage()
+            end
          end
 
          connection:on("receive", onReceive)