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// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/task/sequence_manager/work_queue_sets.h"
#include <optional>
#include "base/check_op.h"
#include "base/task/sequence_manager/task_order.h"
#include "base/task/sequence_manager/work_queue.h"
namespace base::sequence_manager::internal {
WorkQueueSets::WorkQueueSets(const char* name,
Observer* observer,
const SequenceManager::Settings& settings)
: name_(name),
work_queue_heaps_(settings.priority_settings.priority_count()),
#if DCHECK_IS_ON()
last_rand_(settings.random_task_selection_seed),
#endif
observer_(observer) {
}
WorkQueueSets::~WorkQueueSets() = default;
void WorkQueueSets::AddQueue(WorkQueue* work_queue, size_t set_index) {
DCHECK(!work_queue->work_queue_sets());
DCHECK_LT(set_index, work_queue_heaps_.size());
DCHECK(!work_queue->heap_handle().IsValid());
std::optional<TaskOrder> key = work_queue->GetFrontTaskOrder();
work_queue->AssignToWorkQueueSets(this);
work_queue->AssignSetIndex(set_index);
if (!key) {
return;
}
bool was_empty = work_queue_heaps_[set_index].empty();
work_queue_heaps_[set_index].insert({*key, work_queue});
if (was_empty) {
observer_->WorkQueueSetBecameNonEmpty(set_index);
}
}
void WorkQueueSets::RemoveQueue(WorkQueue* work_queue) {
DCHECK_EQ(this, work_queue->work_queue_sets());
work_queue->AssignToWorkQueueSets(nullptr);
if (!work_queue->heap_handle().IsValid()) {
return;
}
size_t set_index = work_queue->work_queue_set_index();
DCHECK_LT(set_index, work_queue_heaps_.size());
work_queue_heaps_[set_index].erase(work_queue->heap_handle());
if (work_queue_heaps_[set_index].empty()) {
observer_->WorkQueueSetBecameEmpty(set_index);
}
DCHECK(!work_queue->heap_handle().IsValid());
}
void WorkQueueSets::ChangeSetIndex(WorkQueue* work_queue, size_t set_index) {
DCHECK_EQ(this, work_queue->work_queue_sets());
DCHECK_LT(set_index, work_queue_heaps_.size());
std::optional<TaskOrder> key = work_queue->GetFrontTaskOrder();
size_t old_set = work_queue->work_queue_set_index();
DCHECK_LT(old_set, work_queue_heaps_.size());
DCHECK_NE(old_set, set_index);
work_queue->AssignSetIndex(set_index);
DCHECK_EQ(key.has_value(), work_queue->heap_handle().IsValid());
if (!key) {
return;
}
work_queue_heaps_[old_set].erase(work_queue->heap_handle());
bool was_empty = work_queue_heaps_[set_index].empty();
work_queue_heaps_[set_index].insert({*key, work_queue});
// Invoke `WorkQueueSetBecameNonEmpty()` before `WorkQueueSetBecameEmpty()` so
// `observer_` doesn't momentarily observe that all work queue sets are empty.
// TaskQueueSelectorTest.TestDisableEnable will fail if the order changes.
if (was_empty) {
observer_->WorkQueueSetBecameNonEmpty(set_index);
}
if (work_queue_heaps_[old_set].empty()) {
observer_->WorkQueueSetBecameEmpty(old_set);
}
}
void WorkQueueSets::OnQueuesFrontTaskChanged(WorkQueue* work_queue) {
size_t set_index = work_queue->work_queue_set_index();
DCHECK_EQ(this, work_queue->work_queue_sets());
DCHECK_LT(set_index, work_queue_heaps_.size());
DCHECK(work_queue->heap_handle().IsValid());
DCHECK(!work_queue_heaps_[set_index].empty()) << " set_index = " << set_index;
if (auto key = work_queue->GetFrontTaskOrder()) {
// O(log n)
work_queue_heaps_[set_index].Replace(work_queue->heap_handle(),
{*key, work_queue});
} else {
// O(log n)
work_queue_heaps_[set_index].erase(work_queue->heap_handle());
DCHECK(!work_queue->heap_handle().IsValid());
if (work_queue_heaps_[set_index].empty()) {
observer_->WorkQueueSetBecameEmpty(set_index);
}
}
}
void WorkQueueSets::OnTaskPushedToEmptyQueue(WorkQueue* work_queue) {
// NOTE if this function changes, we need to keep |WorkQueueSets::AddQueue| in
// sync.
DCHECK_EQ(this, work_queue->work_queue_sets());
std::optional<TaskOrder> key = work_queue->GetFrontTaskOrder();
DCHECK(key);
size_t set_index = work_queue->work_queue_set_index();
DCHECK_LT(set_index, work_queue_heaps_.size())
<< " set_index = " << set_index;
// |work_queue| should not be in work_queue_heaps_[set_index].
DCHECK(!work_queue->heap_handle().IsValid());
bool was_empty = work_queue_heaps_[set_index].empty();
work_queue_heaps_[set_index].insert({*key, work_queue});
if (was_empty) {
observer_->WorkQueueSetBecameNonEmpty(set_index);
}
}
void WorkQueueSets::OnPopMinQueueInSet(WorkQueue* work_queue) {
// Assume that `work_queue` contains the lowest `TaskOrder`.
size_t set_index = work_queue->work_queue_set_index();
DCHECK_EQ(this, work_queue->work_queue_sets());
DCHECK_LT(set_index, work_queue_heaps_.size());
DCHECK(!work_queue_heaps_[set_index].empty()) << " set_index = " << set_index;
DCHECK_EQ(work_queue_heaps_[set_index].top().value, work_queue)
<< " set_index = " << set_index;
DCHECK(work_queue->heap_handle().IsValid());
if (auto key = work_queue->GetFrontTaskOrder()) {
// O(log n)
work_queue_heaps_[set_index].ReplaceTop({*key, work_queue});
} else {
// O(log n)
work_queue_heaps_[set_index].pop();
DCHECK(!work_queue->heap_handle().IsValid());
DCHECK(work_queue_heaps_[set_index].empty() ||
work_queue_heaps_[set_index].top().value != work_queue);
if (work_queue_heaps_[set_index].empty()) {
observer_->WorkQueueSetBecameEmpty(set_index);
}
}
}
void WorkQueueSets::OnQueueBlocked(WorkQueue* work_queue) {
DCHECK_EQ(this, work_queue->work_queue_sets());
HeapHandle heap_handle = work_queue->heap_handle();
if (!heap_handle.IsValid()) {
return;
}
size_t set_index = work_queue->work_queue_set_index();
DCHECK_LT(set_index, work_queue_heaps_.size());
work_queue_heaps_[set_index].erase(heap_handle);
if (work_queue_heaps_[set_index].empty()) {
observer_->WorkQueueSetBecameEmpty(set_index);
}
}
std::optional<WorkQueueAndTaskOrder>
WorkQueueSets::GetOldestQueueAndTaskOrderInSet(size_t set_index) const {
DCHECK_LT(set_index, work_queue_heaps_.size());
if (work_queue_heaps_[set_index].empty()) {
return std::nullopt;
}
const OldestTaskOrder& oldest = work_queue_heaps_[set_index].top();
DCHECK(oldest.value->heap_handle().IsValid());
#if DCHECK_IS_ON()
std::optional<TaskOrder> order = oldest.value->GetFrontTaskOrder();
DCHECK(order && oldest.key == *order);
#endif
return WorkQueueAndTaskOrder(*oldest.value, oldest.key);
}
#if DCHECK_IS_ON()
std::optional<WorkQueueAndTaskOrder>
WorkQueueSets::GetRandomQueueAndTaskOrderInSet(size_t set_index) const {
DCHECK_LT(set_index, work_queue_heaps_.size());
if (work_queue_heaps_[set_index].empty()) {
return std::nullopt;
}
const OldestTaskOrder& chosen =
work_queue_heaps_[set_index].begin()[static_cast<long>(
Random() % work_queue_heaps_[set_index].size())];
#if DCHECK_IS_ON()
std::optional<TaskOrder> key = chosen.value->GetFrontTaskOrder();
DCHECK(key && chosen.key == *key);
#endif
return WorkQueueAndTaskOrder(*chosen.value, chosen.key);
}
#endif
bool WorkQueueSets::IsSetEmpty(size_t set_index) const {
DCHECK_LT(set_index, work_queue_heaps_.size())
<< " set_index = " << set_index;
return work_queue_heaps_[set_index].empty();
}
#if DCHECK_IS_ON() || !defined(NDEBUG)
bool WorkQueueSets::ContainsWorkQueueForTest(
const WorkQueue* work_queue) const {
std::optional<TaskOrder> task_order = work_queue->GetFrontTaskOrder();
for (const auto& heap : work_queue_heaps_) {
for (const OldestTaskOrder& heap_value_pair : heap) {
if (heap_value_pair.value == work_queue) {
DCHECK(task_order);
DCHECK(heap_value_pair.key == *task_order);
DCHECK_EQ(this, work_queue->work_queue_sets());
return true;
}
}
}
if (work_queue->work_queue_sets() == this) {
DCHECK(!task_order);
return true;
}
return false;
}
#endif
void WorkQueueSets::CollectSkippedOverLowerPriorityTasks(
const internal::WorkQueue* selected_work_queue,
std::vector<const Task*>* result) const {
std::optional<TaskOrder> task_order =
selected_work_queue->GetFrontTaskOrder();
CHECK(task_order);
for (size_t priority = selected_work_queue->work_queue_set_index() + 1;
priority < work_queue_heaps_.size(); priority++) {
for (const OldestTaskOrder& pair : work_queue_heaps_[priority]) {
pair.value->CollectTasksOlderThan(*task_order, result);
}
}
}
} // namespace base::sequence_manager::internal
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