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Unified Diff: base/task_scheduler/sequence.h

Issue 1705253002: TaskScheduler [3/9] Task and Sequence (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@s_1_scheduler_lock
Patch Set: self review Created 4 years, 10 months ago
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Index: base/task_scheduler/sequence.h
diff --git a/base/task_scheduler/sequence.h b/base/task_scheduler/sequence.h
new file mode 100644
index 0000000000000000000000000000000000000000..f4e287fb0b329004a81c8ebfdd7ac24628186f12
--- /dev/null
+++ b/base/task_scheduler/sequence.h
@@ -0,0 +1,69 @@
+// 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_SEQUENCE_H_
+#define BASE_TASK_SCHEDULER_SEQUENCE_H_
+
+#include <stddef.h>
+
+#include <queue>
+
+#include "base/base_export.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/task_scheduler/scheduler_lock.h"
+#include "base/task_scheduler/sequence_sort_key.h"
+#include "base/task_scheduler/task.h"
+#include "base/task_scheduler/task_traits.h"
+
+namespace base {
+namespace internal {
+
+// A sequence holds tasks that must be executed in posting order. This class is
robliao 2016/02/19 02:33:43 Nit: Linebreak after the period here is okay.
fdoray 2016/02/19 14:12:14 Done.
+// thread-safe.
+class BASE_EXPORT Sequence : public RefCountedThreadSafe<Sequence> {
+ public:
+ Sequence();
+
+ // Adds |task| at the end of the sequence's queue. Returns true if the
+ // sequence was empty before this operation.
+ bool PushTask(scoped_ptr<Task> task);
+
+ // Returns the task in front of the sequence's queue, if any.
+ const Task* PeekTask() const;
+
+ // Removes the task in front of the sequence's queue. Returns true if the
+ // sequence is empty after this operation. Cannot be called on an empty
+ // sequence.
+ bool PopTask();
+
+ // Returns a SequenceSortKey to use when inserting the sequence in a priority
+ // queue. Cannot be called on an empty sequence.
+ SequenceSortKey GetSortKey() const;
+
+ private:
+ friend class RefCountedThreadSafe<Sequence>;
+ ~Sequence();
+
+ // Controls access to all members.
robliao 2016/02/19 02:33:43 Nit: Synchronizes access to all members.
fdoray 2016/02/19 14:12:14 Done.
+ mutable SchedulerLock lock_;
+
+ // Queue of tasks to execute.
+ std::queue<scoped_ptr<Task>> queue_;
+
+ // Number of task priorities in the TaskPriority enum.
+ static const size_t kNumTaskPriorities =
robliao 2016/02/19 02:33:43 Shouldn't this be taken from task_traits.h?
fdoray 2016/02/19 14:12:14 Done.
+ static_cast<TaskPriorityUnderlyingType>(TaskPriority::HIGHEST) + 1;
robliao 2016/02/19 02:33:43 This seems like something that should remain at or
fdoray 2016/02/19 14:12:14 Done.
+
+ // Number of tasks contained in the sequence for each priority.
+ size_t num_tasks_per_priority_[kNumTaskPriorities] = {};
+
+ DISALLOW_COPY_AND_ASSIGN(Sequence);
+};
+
+} // namespace internal
+} // namespace base
+
+#endif // BASE_TASK_SCHEDULER_SEQUENCE_H_

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