text: /*
   * Copyright (c) 2013 Matt Fichman
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to
   * deal in the Software without restriction, including without limitation the
   * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
   * sell copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   * 
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   * 
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, APEXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
   * IN THE SOFTWARE.
   */
  
  namespace coro {
  
  void Hub::poll() {
  // Poll For I/O events.  If there are pending coroutines, then don't block
  // indefinitely -- just check for any ready I/O.  If there are timers, block
  // only until the min timer is ready.
      size_t tasks = runnable_.size()+timeout_.size();
      DWORD timeout = 0;
      if (!timeout_.empty() && runnable_.empty()) {
          auto const diff = timeout_.top().time()-Time::now();
          if (diff > Time::sec(0)) {
              timeout = DWORD(diff.millisec());
          }
      }
      if (tasks <= 0) {
          timeout = INFINITE;
      }
      if (timeout == 0 && blocked_ == 0) {
          return;
      }
      SetLastError(ERROR_SUCCESS);
      ULONG_PTR udata = 0;
      Overlapped* op = 0;
      OVERLAPPED** evt = (OVERLAPPED**)&op;
      DWORD bytes = 0;
      BOOL ret = GetQueuedCompletionStatus(handle_, (LPDWORD)&bytes, &udata, evt, timeout);
      if (!op) { return; }
      if (ret) {
          op->bytes = bytes;
          op->error = ERROR_SUCCESS;
      } else {
          op->bytes = 0;
          op->error = GetLastError();
      }
      auto const coro = (Coroutine*)op->coroutine;
      assert(coro->status()!=Coroutine::EXITED);
      coro->unblock();
  }
  
  }
  