101 lines
3.7 KiB
C++
101 lines
3.7 KiB
C++
// Copyright 2016 The Chromium Authors
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_TASK_THREAD_POOL_PRIORITY_QUEUE_H_
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#define BASE_TASK_THREAD_POOL_PRIORITY_QUEUE_H_
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#include <functional>
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#include <memory>
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#include "base/base_export.h"
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#include "base/containers/intrusive_heap.h"
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#include "base/task/common/checked_lock.h"
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#include "base/task/thread_pool/task_source.h"
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#include "base/task/thread_pool/task_source_sort_key.h"
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#include "base/types/cxx23_to_underlying.h"
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namespace base {
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namespace internal {
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// A PriorityQueue holds TaskSources of Tasks. This class is not thread-safe
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// (requires external synchronization).
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class BASE_EXPORT PriorityQueue {
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public:
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PriorityQueue();
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PriorityQueue(const PriorityQueue&) = delete;
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PriorityQueue& operator=(const PriorityQueue&) = delete;
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~PriorityQueue();
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PriorityQueue& operator=(PriorityQueue&& other);
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// Inserts |task_source| in the PriorityQueue with |task_source_sort_key|.
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void Push(RegisteredTaskSource task_source,
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TaskSourceSortKey task_source_sort_key);
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// Returns a reference to the TaskSourceSortKey representing the priority of
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// the highest pending task in this PriorityQueue. The reference becomes
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// invalid the next time that this PriorityQueue is modified.
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// Cannot be called on an empty PriorityQueue.
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const TaskSourceSortKey& PeekSortKey() const;
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// Returns a reference to the highest priority TaskSource in this
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// PriorityQueue. Cannot be called on an empty PriorityQueue. The returned
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// task source may be modified as long as its sort key isn't affected.
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RegisteredTaskSource& PeekTaskSource() const;
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// Removes and returns the highest priority TaskSource in this PriorityQueue.
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// Cannot be called on an empty PriorityQueue.
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RegisteredTaskSource PopTaskSource();
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// Removes |task_source| from the PriorityQueue. Returns a
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// RegisteredTaskSource which evaluates to true if successful, or false if
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// |task_source| is not currently in the PriorityQueue or the PriorityQueue is
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// empty.
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RegisteredTaskSource RemoveTaskSource(const TaskSource& task_source);
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// Updates the sort key of |task_source| to |sort_key|, reordering
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// |task_source| in the queue if necessary. No-ops if the TaskSource is not in
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// the PriorityQueue or the PriorityQueue is empty.
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void UpdateSortKey(const TaskSource& task_source, TaskSourceSortKey sort_key);
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// Returns true if the PriorityQueue is empty.
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bool IsEmpty() const;
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// Returns the number of TaskSources in the PriorityQueue.
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size_t Size() const;
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// Returns the number of TaskSources with |priority|.
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size_t GetNumTaskSourcesWithPriority(TaskPriority priority) const {
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return num_task_sources_per_priority_[base::to_underlying(priority)];
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}
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// Set the PriorityQueue to empty all its TaskSources of Tasks when it is
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// destroyed; needed to prevent memory leaks caused by a reference cycle
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// (TaskSource -> Task -> TaskRunner -> TaskSource...) during test teardown.
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void EnableFlushTaskSourcesOnDestroyForTesting();
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private:
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// A class combining a TaskSource and the TaskSourceSortKey that determines
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// its position in a PriorityQueue.
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class TaskSourceAndSortKey;
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using ContainerType = IntrusiveHeap<TaskSourceAndSortKey>;
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void DecrementNumTaskSourcesForPriority(TaskPriority priority);
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void IncrementNumTaskSourcesForPriority(TaskPriority priority);
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ContainerType container_;
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std::array<size_t, static_cast<int>(TaskPriority::HIGHEST) + 1>
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num_task_sources_per_priority_ = {};
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// Should only be enabled by EnableFlushTaskSourcesOnDestroyForTesting().
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bool is_flush_task_sources_on_destroy_enabled_ = false;
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};
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} // namespace internal
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} // namespace base
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#endif // BASE_TASK_THREAD_POOL_PRIORITY_QUEUE_H_
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