TaskScheduler [10] SchedulerWorkerThreadStack

base/task_scheduler/scheduler_worker_thread_stack.h

+// Copyright 2016 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 BASE_TASK_SCHEDULER_SCHEDULER_WORKER_THREAD_STACK_H_
+#define BASE_TASK_SCHEDULER_SCHEDULER_WORKER_THREAD_STACK_H_
+
+#include <stddef.h>
+
+#include <vector>
+
+#include "base/base_export.h"
+#include "base/macros.h"
+
+namespace base {
+namespace internal {
+
+class SchedulerWorkerThread;
+
+// A stack of SchedulerWorkerThreads. Supports removal of arbitrary
+// SchedulerWorkerThreads. DCHECKs when a SchedulerWorkerThread is inserted
+// multiple times. SchedulerWorkerThreads are not owned by the stack. Push() is
+// amortized O(1). Pop(), Size() and Empty() are O(1). Remove is O(n). This
+// class is NOT thread-safe.
+class BASE_EXPORT SchedulerWorkerThreadStack {
+ public:
+  SchedulerWorkerThreadStack();
+  ~SchedulerWorkerThreadStack();
+
+  // Inserts |worker_thread| at the top of the stack. |worker_thread| must not
+  // already be on the stack.
+  void Push(SchedulerWorkerThread* worker_thread);
+
+  // Removes the top SchedulerWorkerThread from the stack and returns it.
+  // Returns nullptr if the stack is empty.
+  SchedulerWorkerThread* Pop();
+
+  // Removes |worker_thread| from the stack.
+  void Remove(const SchedulerWorkerThread* worker_thread);
+
+  // Returns the number of SchedulerWorkerThreads on the stack.
+  size_t Size() const { return stack_.size(); }
+
+  // Returns true if the stack is empty.
+  bool IsEmpty() const { return stack_.empty(); }
+
+ private:
+  std::vector<SchedulerWorkerThread*> stack_;
+
+  DISALLOW_COPY_AND_ASSIGN(SchedulerWorkerThreadStack);
+};
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_TASK_SCHEDULER_SCHEDULER_WORKER_THREAD_STACK_H_