Libuv event loop

[PerilousApricot]

I'm wondering if there is a way to use libuv in the background. I've tried the following in init_worker_by_file, and it appears that while the timers fire and the thread is started, subsequent requests never get control:

local uv = require('luv')
local ngx = require('ngx')
print("Initializing worker (hopefully)")
local function my_loop_init_timer(premature)
  -- This timer is run in init context and (hopefully) will let us start a
  -- light thread in the worker context
  local function my_loop_thread()
    -- this hopefully persists for the lifetime of the worker
    print("UV thread executing, uv FD is: " .. uv.backend_fd())
    while ngx.worker.exiting() == false do
      -- I know this is busy waiting, but I don't know another way to tell lua-nginx to poll the fd
      while uv.run("nowait") do
        coroutine.yield()
      end
      coroutine.yield()
      uv.sleep(1)
    end
  end
  ngx.thread.spawn(my_loop_thread)
end
print("Main interpreter is running, uv FD is: " .. uv.backend_fd())

ngx.timer.at(0, my_loop_init_timer)

[DuskRavenVII]

Try using uv.run(), it might solve your problem.

[PerilousApricot]

Hi @DuskRavenVII I'd hope it would, but it either blocks (uv.run()) or returns possibly before the I/O is complete (uv.run("nowait")), I'm looking for a way to get the event loop running asynchronously/in the background, and I'm missing how to do that within openresty

[PerilousApricot]

I'd like to replace what is primarily a file i/o HTTP interface (with some extra parts, which is why the regular sendfile() and friends functionality doesn't work), but it appears there's no non-blocking file i/o within either lua itself, or in lua-nginx-module, which is what led me down the path of attempting to use libuv. Is this a pattern you've seen before?

[DuskRavenVII]

Use uv.run() in a separate thread and make sure that uv.run("nowait") is continuously checking for I/O operations.