1 // Copyright 2016 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "base/task_scheduler/sequence.h" 6 7 #include <utility> 8 9 #include "base/logging.h" 10 #include "base/time/time.h" 11 12 namespace base { 13 namespace internal { 14 15 Sequence::Sequence() = default; 16 17 bool Sequence::PushTask(std::unique_ptr<Task> task) { 18 DCHECK(task->sequenced_time.is_null()); 19 task->sequenced_time = base::TimeTicks::Now(); 20 21 AutoSchedulerLock auto_lock(lock_); 22 ++num_tasks_per_priority_[static_cast<int>(task->traits.priority())]; 23 queue_.push(std::move(task)); 24 25 // Return true if the sequence was empty before the push. 26 return queue_.size() == 1; 27 } 28 29 const Task* Sequence::PeekTask() const { 30 AutoSchedulerLock auto_lock(lock_); 31 32 if (queue_.empty()) 33 return nullptr; 34 35 return queue_.front().get(); 36 } 37 38 bool Sequence::PopTask() { 39 AutoSchedulerLock auto_lock(lock_); 40 DCHECK(!queue_.empty()); 41 42 const int priority_index = 43 static_cast<int>(queue_.front()->traits.priority()); 44 DCHECK_GT(num_tasks_per_priority_[priority_index], 0U); 45 --num_tasks_per_priority_[priority_index]; 46 47 queue_.pop(); 48 return queue_.empty(); 49 } 50 51 SequenceSortKey Sequence::GetSortKey() const { 52 TaskPriority priority = TaskPriority::LOWEST; 53 base::TimeTicks next_task_sequenced_time; 54 55 { 56 AutoSchedulerLock auto_lock(lock_); 57 DCHECK(!queue_.empty()); 58 59 // Find the highest task priority in the sequence. 60 const int highest_priority_index = static_cast<int>(TaskPriority::HIGHEST); 61 const int lowest_priority_index = static_cast<int>(TaskPriority::LOWEST); 62 for (int i = highest_priority_index; i > lowest_priority_index; --i) { 63 if (num_tasks_per_priority_[i] > 0) { 64 priority = static_cast<TaskPriority>(i); 65 break; 66 } 67 } 68 69 // Save the sequenced time of the next task in the sequence. 70 next_task_sequenced_time = queue_.front()->sequenced_time; 71 } 72 73 return SequenceSortKey(priority, next_task_sequenced_time); 74 } 75 76 Sequence::~Sequence() = default; 77 78 } // namespace internal 79 } // namespace base 80
