text: // Copyright 2013 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #include "mojo/edk/system/awakable_list.h"
  
  #include <algorithm>
  
  #include "base/logging.h"
  #include "mojo/edk/system/awakable.h"
  #include "mojo/edk/system/handle_signals_state.h"
  
  namespace mojo {
  namespace system {
  
  AwakableList::AwakableList() {
  }
  
  AwakableList::~AwakableList() {
    DCHECK(awakables_.empty());
  }
  
  void AwakableList::AwakeForStateChange(const HandleSignalsState& state) {
    // Instead of deleting elements in-place, swap them with the last element and
    // erase the elements from the end.
    auto last = awakables_.end();
    for (AwakeInfoList::iterator it = awakables_.begin(); it != last;) {
      bool keep = true;
      if (state.satisfies(it->signals))
        keep = it->awakable->Awake(MOJO_RESULT_OK, it->context);
      else if (!state.can_satisfy(it->signals))
        keep = it->awakable->Awake(MOJO_RESULT_FAILED_PRECONDITION, it->context);
  
      if (!keep) {
        --last;
        std::swap(*it, *last);
      } else {
        ++it;
      }
    }
    awakables_.erase(last, awakables_.end());
  }
  
  void AwakableList::CancelAll() {
    for (AwakeInfoList::iterator it = awakables_.begin(); it != awakables_.end();
         ++it) {
      it->awakable->Awake(MOJO_RESULT_CANCELLED, it->context);
    }
    awakables_.clear();
  }
  
  void AwakableList::Add(Awakable* awakable,
                         MojoHandleSignals signals,
                         uint32_t context) {
    awakables_.push_back(AwakeInfo(awakable, signals, context));
  }
  
  void AwakableList::Remove(Awakable* awakable) {
    // We allow a thread to wait on the same handle multiple times simultaneously,
    // so we need to scan the entire list and remove all occurrences of |waiter|.
    auto last = awakables_.end();
    for (AwakeInfoList::iterator it = awakables_.begin(); it != last;) {
      if (it->awakable == awakable) {
        --last;
        std::swap(*it, *last);
      } else {
        ++it;
      }
    }
    awakables_.erase(last, awakables_.end());
  }
  
  }  // namespace system
  }  // namespace mojo
  