TaskScheduler [10] SchedulerWorkerThreadStack

base/task_scheduler/scheduler_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_STACK_H_
+#define BASE_TASK_SCHEDULER_SCHEDULER_STACK_H_
+
+#include <stddef.h>
+
+#include <algorithm>
+#include <vector>
+
+#include "base/logging.h"
+#include "base/macros.h"
+
+namespace base {
+namespace internal {
+
+// A stack that supports removal of arbitrary values and doesn't allow multiple
+// insertions of the same value.
+

[robliao, 2016/04/20 20:54:58]

Remove extra linebreak.

[fdoray, 2016/04/20 21:04:41]

Done.

+// This class is NOT thread-safe.
+template <typename T>
+class SchedulerStack {

[robliao, 2016/04/20 20:54:58]

Given that this doesn't allow multiple insertions of the same value, maybe
SchedulerUniqueStack?

[fdoray, 2016/04/20 21:04:41]

Done.

+ public:
+  SchedulerStack();
+  ~SchedulerStack();
+
+  // Inserts |val| at the top of the stack. |val| must not already be on the
+  // stack.
+  void Push(const T& val);
+
+  // Removes the top value from the stack and returns it. Cannot be called on an
+  // empty stack.
+  T Pop();

[robliao, 2016/04/20 20:54:58]

Would peek be a useful operation that we may use in the future?

[fdoray, 2016/04/20 21:04:41]

We don't need it currently. With this API, we can do stack.Pop()->WakeUp()

I prefer not to add methods that aren't used.

+
+  // Removes |val| from the stack if it was on it.
+  void Remove(const T& val);
+
+  // Returns the number of values on the stack.
+  size_t Size() const;
+
+  // Returns true if the stack is empty.
+  bool Empty() const;
+
+ private:
+  std::vector<T> stack_;
+
+  DISALLOW_COPY_AND_ASSIGN(SchedulerStack);
+};
+
+template <typename T>
+SchedulerStack<T>::SchedulerStack() = default;
+
+template <typename T>
+SchedulerStack<T>::~SchedulerStack() = default;
+
+template <typename T>
+void SchedulerStack<T>::Push(const T& val) {
+  DCHECK(std::find(stack_.begin(), stack_.end(), val) == stack_.end())
+      << "Value already on stack";
+  stack_.push_back(val);
+}
+
+template <typename T>
+T SchedulerStack<T>::Pop() {
+  DCHECK(!stack_.empty());
+  const T val = stack_.back();
+  stack_.pop_back();
+  return val;
+}
+
+template <typename T>
+void SchedulerStack<T>::Remove(const T& val) {
+  auto it = std::find(stack_.begin(), stack_.end(), val);
+  if (it != stack_.end())
+    stack_.erase(it);
+}
+
+template <typename T>
+size_t SchedulerStack<T>::Size() const {
+  return stack_.size();
+}
+
+template <typename T>
+bool SchedulerStack<T>::Empty() const {
+  return stack_.empty();
+}
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_TASK_SCHEDULER_SCHEDULER_STACK_H_