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// 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.
#include "base/task_scheduler/sequence.h"
#include <utility>
#include "base/logging.h"
#include "base/time/time.h"
namespace base {
namespace internal {
Sequence::Sequence() = default;
bool Sequence::PushTask(std::unique_ptr<Task> task) {
DCHECK(task);
DCHECK(task->task);
DCHECK(task->sequenced_time.is_null());
task->sequenced_time = base::TimeTicks::Now();
AutoSchedulerLock auto_lock(lock_);
++num_tasks_per_priority_[static_cast<int>(task->traits.priority())];
queue_.push(std::move(task));
// Return true if the sequence was empty before the push.
return queue_.size() == 1;
}
std::unique_ptr<Task> Sequence::TakeTask() {
AutoSchedulerLock auto_lock(lock_);
DCHECK(!queue_.empty());
DCHECK(queue_.front());
const int priority_index =
static_cast<int>(queue_.front()->traits.priority());
DCHECK_GT(num_tasks_per_priority_[priority_index], 0U);
--num_tasks_per_priority_[priority_index];
return std::move(queue_.front());
}
TaskTraits Sequence::PeekTaskTraits() const {
AutoSchedulerLock auto_lock(lock_);
DCHECK(!queue_.empty());
DCHECK(queue_.front());
return queue_.front()->traits;
}
bool Sequence::Pop() {
AutoSchedulerLock auto_lock(lock_);
DCHECK(!queue_.empty());
DCHECK(!queue_.front());
queue_.pop();
return queue_.empty();
}
SequenceSortKey Sequence::GetSortKey() const {
TaskPriority priority = TaskPriority::LOWEST;
base::TimeTicks next_task_sequenced_time;
{
AutoSchedulerLock auto_lock(lock_);
DCHECK(!queue_.empty());
// Find the highest task priority in the sequence.
const int highest_priority_index = static_cast<int>(TaskPriority::HIGHEST);
const int lowest_priority_index = static_cast<int>(TaskPriority::LOWEST);
for (int i = highest_priority_index; i > lowest_priority_index; --i) {
if (num_tasks_per_priority_[i] > 0) {
priority = static_cast<TaskPriority>(i);
break;
}
}
// Save the sequenced time of the next task in the sequence.
next_task_sequenced_time = queue_.front()->sequenced_time;
}
return SequenceSortKey(priority, next_task_sequenced_time);
}
Sequence::~Sequence() = default;
} // namespace internal
} // namespace base
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