StaticFileHandler

[markuman]

This works fine. So 127.0.0.1:8000/download will start transfering file.zip.

local app = turbo.web.Application(
  {
    {"^/download$", turbo.web.StaticFileHandler, "file.zip"},
  })

But what when I don't want the static "download" address and want to start a transfer more dynamically.

Currently I'm doing

local f = assert(io.open("file.zip", "rb")) -- read binary
local t = f:read("*all")
f:close()  
self:write(t)

But this has a huge ram consumption when the transfering files are large. Any ideas how to handle this in a better way?

[kernelsauce]

Hi yes, this is possible to do :).

You read appropriate amount of bytes and then send that off and wait until it has been sent before sending next chunk.

Open up web.lua and look at the StaticFileHandler which does exactly that.

But basically its something like this (in pseudo code);

self:set_chunked_write()
while (true) {
    local chunk = f:read(some_bytes)
    ... if still data ...
    self:write(chunk)
    coroutine.yield (turbo.async.task(turbo.web.RequestHandler.flush, self))
}
self:finish()

[markuman]

Thank you, got it now.

self:add_header('Content-Type', 'application/octet-stream')
self:add_header('Content-Disposition', 'attachment; filename=' .. filename)
local f = assert(io.open(filename, "rb")) -- read binary
local current = f:seek()      -- get current position
local size = f:seek('end')    -- get file size
f:seek('set', current)        -- restore position
self:add_header('Content-Length', size)
while true do
  local chunk = f:read(1024 * 32) -- 32kb chunks
  if not chunk then break end        
  self:write(chunk)        
  coroutine.yield (turbo.async.task(turbo.web.RequestHandler.flush, self))
end
f:close()
self:finish()

The Content-Length header is important too :)

[kernelsauce]

Content length is required if you do not use chunked encoding as suggested. Otherwise your way works fine too. søn. 20. sep. 2015 kl. 09.13 skrev Markus Bergholz <notifications@github.com

:

Closed #231 https://github.com/kernelsauce/turbo/issues/231.

— Reply to this email directly or view it on GitHub https://github.com/kernelsauce/turbo/issues/231#event-414098307.

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