fixit.nim

when hostOS == "windows":
  const
    MAXIMUM_WAIT_OBJECTS = 64
    MAXIMUM_WAIT_THREADS = MAXIMUM_WAIT_OBJECTS * MAXIMUM_WAIT_OBJECTS

  type
    WaitChunk = object
      events: array[MAXIMUM_WAIT_OBJECTS, SysThread]
      count: int

  proc createThread*[TArg](t: var Thread[TArg],
                           tp: proc (arg: TArg) {.thread, nimcall.},
                           param: TArg)

  proc threadWait(chunk: WaitChunk) {.thread.} =
    echo "threadWait(" & $chunk.count & ")"
    discard waitForMultipleObjects(int32(chunk.count),
                                cast[ptr SysThread](unsafeAddr chunk.events[0]),
                                   1, -1);

  proc joinThread*[TArg](t: Thread[TArg]) {.inline.} =
    ## waits for the thread `t` to finish.
    discard waitForSingleObject(t.sys, -1'i32)

  proc joinThreads*[TArg](t: varargs[Thread[TArg]]) =
    ## waits for every thread in `t` to finish.
    sysAssert(len(t) <= MAXIMUM_WAIT_THREADS,
              "Maximum number of threads reached")
    if len(t) > MAXIMUM_WAIT_OBJECTS:
      var count = 0
      var thrs: array[MAXIMUM_WAIT_OBJECTS, SysThread]
      var thread: Thread[WaitChunk]
      var s = 0
      var chunk = WaitChunk()
      while true:
        var e = min(t.len, s + MAXIMUM_WAIT_OBJECTS)
        var k = 0
        echo "s = " & $s
        echo "e = " & $e
        for i in s..(e - 1):
          echo "put " & $i & " thread " & $t[i].sys & " to wait chunk"
          chunk.events[k] = t[i].sys
          inc(k)
        chunk.count = k
        echo "running wait thread with " & $chunk.count & " events"
        createThread(thread, threadWait, chunk)
        thrs[count] = thread.sys
        inc(count)
        if e == t.len: break
        inc(s, MAXIMUM_WAIT_OBJECTS)
        
      echo "wait for " & $count & " threads..."
      echo repr thrs
      discard waitForMultipleObjects(int32(count),
                                     cast[ptr SysThread](addr thrs[0]),
                                     1, -1)
      echo "wait completed!"
    else:
      var a: array[MAXIMUM_WAIT_OBJECTS, SysThread]
      for i in 0..t.high: a[i] = t[i].sys
      discard waitForMultipleObjects(t.len.int32,
                                     cast[ptr SysThread](addr(a)), 1, -1)