Mirror of forum.nim-lang.org

10189 :: fswatch, non blocking usage?

• alexeypetrushin (orginal) [2023-05-10T12:51:12+02:00] view original

  There's a Nim binding for the fswatch C-library, to watch for file system events https://github.com/paul-nameless/nim-fswatch

  Would it be possible to use it with the async HTTP server?

  I wrote example but it's not working with async server properly. If you open the HTTP page, it just waits and never respond.

  import std/[httpcore, asynchttpserver, asyncnet, asyncdispatch]
  import libfswatch, libfswatch/fswatch
  
  # DB ----------------------------------------------------------
  type DB = ref object
    events: seq[string]
  
  let db = DB()
  
  # HTTP Server -------------------------------------------------
  proc handler(req: Request): Future[void] {.async, gcsafe.} =
    let content = $(db[])
    await req.respond(Http200, content)
  
  var server = new_async_http_server()
  async_check server.serve(Port(4000), handler, "localhost")
  
  # FS Watch ----------------------------------------------------
  proc callback(event: fsw_cevent, event_num: cuint) =
    db.events.add $(event.path)
    echo $(db[])
  
  var mon = newMonitor()
  
  mon.addPath(".")
  mon.setCallback(callback)
  mon.start()   # <= Blocking call that seems to break async
  run_forever() # <= This line never called
  Run

---

• blackmius (orginal) [2023-05-10T14:00:29+02:00] view original

  fswatch is apparently an event loop itself. To run them both at the same time, they must be launched in different threads and communicate between them through the means of communication of threads of the Channel type. But this will greatly complicate your program, so look for analogues of fswatch but for asyncdispatch nim

---

• alexeypetrushin (orginal) [2023-05-10T14:59:54+02:00] view original

  Thanks, I checked that thread, but seems like the async library https://github.com/Vindaar/fsmonitor2 supports linux only, I'm using mac os.

  P.S. There's also bruteforce option, diff path tree periodically, going to use it for now :)

---