scheduler: Add a base directory

components/scheduler/child/task_queue_sets.h

-// Copyright 2015 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.
-
-#ifndef COMPONENTS_SCHEDULER_CHILD_TASK_QUEUE_SETS_H_
-#define COMPONENTS_SCHEDULER_CHILD_TASK_QUEUE_SETS_H_
-
-#include <map>
-#include <vector>
-
-#include "base/macros.h"
-#include "base/trace_event/trace_event_argument.h"
-#include "components/scheduler/child/task_queue.h"
-#include "components/scheduler/scheduler_export.h"
-
-namespace scheduler {
-namespace internal {
-class TaskQueueImpl;
-
-class SCHEDULER_EXPORT TaskQueueSets {
- public:
-  explicit TaskQueueSets(size_t num_sets);
-  ~TaskQueueSets();
-
-  // O(log num queues)
-  void RemoveQueue(internal::TaskQueueImpl* queue);
-
-  // O(log num queues)
-  void AssignQueueToSet(internal::TaskQueueImpl* queue, size_t set_index);
-
-  // O(log num queues)
-  void OnPushQueue(internal::TaskQueueImpl* queue);
-
-  // If empty it's O(1) amortized, otherwise it's O(log num queues)
-  void OnPopQueue(internal::TaskQueueImpl* queue);
-
-  // O(1)
-  bool GetOldestQueueInSet(size_t set_index,
-                           internal::TaskQueueImpl** out_queue) const;
-
-  // O(1)
-  bool IsSetEmpty(size_t set_index) const;
-
- private:
-  struct EnqueueOrderComparitor {
-    // The enqueueorder numbers are generated in sequence.  These will
-    // eventually overflow and roll-over to negative numbers.  We must take care
-    // to preserve the ordering of the map when this happens.
-    // NOTE we assume that tasks don't get starved for extended periods so that
-    // the task queue ages in a set have at most one roll-over.
-    // NOTE signed integer overflow behavior is undefined in C++ so we can't
-    // use the (a - b) < 0 trick here, because the optimizer won't necessarily
-    // do what we expect.
-    // TODO(alexclarke): Consider making age and sequence_num unsigned, because
-    // unsigned integer overflow behavior is defined.
-    bool operator()(int a, int b) const {
-      if (a < 0 && b >= 0)
-        return false;
-      if (b < 0 && a >= 0)
-        return true;
-      return a < b;
-    }
-  };
-
-  typedef std::map<int, internal::TaskQueueImpl*, EnqueueOrderComparitor>
-      EnqueueOrderToQueueMap;
-  std::vector<EnqueueOrderToQueueMap> enqueue_order_to_queue_maps_;
-
-  DISALLOW_COPY_AND_ASSIGN(TaskQueueSets);
-};
-
-}  // namespace internal
-}  // namespace scheduler
-
-#endif  // COMPONENTS_SCHEDULER_CHILD_TASK_QUEUE_SETS_H_