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3382 :: async from dll; gc.nim SIGSEGV;

• enthus1ast (orginal) [2017-11-29T19:29:27+01:00] view original

  Calling poll on an dynamically loaded module results in

  
  Traceback (most recent call last)
  module.nim(15)           init
  asyncmacro.nim(393)      foo
  asyncmacro.nim(43)       cb0
  asyncfutures.nim(210)    callback=
  asyncfutures.nim(181)    clearCallbacks
  gc.nim(271)              asgnRef
  gc.nim(224)              decRef
  SIGSEGV: Illegal storage access. (Attempt to read from nil?)
  Run

  file loader.nim

  import options, dynlib
  import state
  type
    InitProc = proc(state:State): State {.nimcall.}
    PollProc = proc(state:State): State {.nimcall.}
    
    Module* = object
      init*: InitProc
      poll*: PollProc
      lib: LibHandle
  
  proc loadModule*(path:string): Option[Module] =
    let lib = loadLib(path)
    if lib != nil:
      let initAddr = lib.symAddr("init")
      let pollAddr = lib.symAddr("poll")
      if initAddr != nil and pollAddr != nil:
        let init = cast[InitProc](initAddr)
        let poll = cast[PollProc](pollAddr)
        var module = Module()
        module.init = init
        module.poll = poll
        result = some module
      else:
        echo "Could not find procs"
        return
  
  var module = loadModule("./libmodule.so").get()
  var tststate = State()
  tststate.foo = "test"
  tststate = module.init(tststate) # register async func
  while true:
    tststate = module.poll(tststate)
  Run

  file module.nim

  # module (as shared object):
  # nim c --app:lib module.nim
  import asyncdispatch
  import state
  
  proc foo(): Future[void] {.async.} =
    echo "foo started"
    while true:
      await sleepAsync(250)
  
  {.push dynlib exportc.}
  proc init*(state: State): State =
    asyncCheck foo()
    return state
  
  proc poll*(state: State): State =
    poll()
    return state
  {.pop.}
  
  Run

  file state.nim

  
  type State* = object
    foo*: string
  
  Run

  
  nim c --app:lib module.nim
  nim c -r loader.nim
  
  foo started
  Traceback (most recent call last)
  module.nim(15)           init
  asyncmacro.nim(393)      foo
  asyncmacro.nim(43)       cb0
  asyncfutures.nim(210)    callback=
  asyncfutures.nim(181)    clearCallbacks
  gc.nim(271)              asgnRef
  gc.nim(224)              decRef
  SIGSEGV: Illegal storage access. (Attempt to read from nil?)
  Error: execution of an external program failed: '/home/z/loader'
  Run

  edit:

  it works when module.nim is imported without the call to loadModule.

  What have i done wrong?

---

• Araq (orginal) [2017-11-30T12:14:16+01:00] view original

  Did you use nimrtl.dll as the docs describe? https://nim-lang.org/docs/nimc.html#dll-generation

---

• enthus1ast (orginal) [2017-11-30T17:15:32+01:00] view original

  i created the nimrtl dynamic library and also copied it to the project folder. then when compiled like so:

  nim c --app:lib -d:useNimRtl  module.nim
  Run

  this gets thrown:

  Hint: used config file '/home/z/Nim/config/nim.cfg' [Conf]
  Hint: system [Processing]
  Hint: module [Processing]
  Hint: asyncdispatch [Processing]
  Hint: os [Processing]
  Hint: strutils [Processing]
  Hint: parseutils [Processing]
  Hint: math [Processing]
  Hint: algorithm [Processing]
  Hint: times [Processing]
  Hint: posix [Processing]
  Hint: ospaths [Processing]
  Hint: tables [Processing]
  Hint: hashes [Processing]
  Hint: heapqueue [Processing]
  Hint: lists [Processing]
  Hint: options [Processing]
  Hint: typetraits [Processing]
  Hint: asyncstreams [Processing]
  Hint: asyncfutures [Processing]
  Hint: deques [Processing]
  Hint: nativesockets [Processing]
  Hint: net [Processing]
  Hint: sets [Processing]
  Hint: selectors [Processing]
  Hint: epoll [Processing]
  Hint: macros [Processing]
  lib/pure/asyncdispatch.nim(1545, 61) template/generic instantiation from here
  lib/pure/asyncmacro.nim(301, 55) Error: cannot 'importc' variable at compile time
  Run

  This happens also to a one line test file

  import asyncdispatch
  Run

  edit: opened issue https://github.com/nim-lang/Nim/issues/6855

---