TaskScheduler [4/9] Priority Queue

base/task_scheduler/priority_queue.cc

+// 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/priority_queue.h"
+
+#include "base/logging.h"
+#include "base/task_scheduler/sequence_sort_key.h"
+
+namespace base {
+namespace internal {
+
+PriorityQueue::PriorityQueue(const Closure& sequence_inserted_callback)
+    : sequence_inserted_callback_(sequence_inserted_callback) {
+  DCHECK(!sequence_inserted_callback_.is_null());
+}
+
+PriorityQueue::PriorityQueue(const Closure& sequence_inserted_callback,
+                             PriorityQueue* predecessor_priority_queue)
+    : lock_(&predecessor_priority_queue->lock_),
+      sequence_inserted_callback_(sequence_inserted_callback) {
+  DCHECK(!sequence_inserted_callback_.is_null());
+}
+
+PriorityQueue::~PriorityQueue() = default;
+
+bool PriorityQueue::UnsynchronizedEmpty() const {
+  return container_.empty();
+}
+
+PriorityQueue::Transaction::~Transaction() {
+  DCHECK(CalledOnValidThread());
+  auto_lock_.reset();
+  for (size_t i = 0; i < num_pushed_sequences_; ++i)
+    priority_queue_->sequence_inserted_callback_.Run();
+}
+
+void PriorityQueue::Transaction::PushSequence(scoped_refptr<Sequence> sequence,
+                                              const SequenceSortKey& sort_key) {
+  DCHECK(CalledOnValidThread());
+  priority_queue_->container_.push(
+      std::make_pair(std::move(sequence), sort_key));
+  ++num_pushed_sequences_;
+}
+
+scoped_refptr<Sequence> PriorityQueue::Transaction::PeekSequence(
+    SequenceSortKey* sort_key) const {
+  DCHECK(CalledOnValidThread());
+  DCHECK(sort_key);
+
+  if (priority_queue_->container_.empty())
+    return scoped_refptr<Sequence>();
+
+  *sort_key = priority_queue_->container_.top().second;
+  return priority_queue_->container_.top().first;
+}
+
+void PriorityQueue::Transaction::PopSequence() {
+  DCHECK(CalledOnValidThread());
+  DCHECK(!priority_queue_->container_.empty());
+  priority_queue_->container_.pop();
+}
+
+PriorityQueue::Transaction::Transaction(PriorityQueue* priority_queue)
+    : priority_queue_(priority_queue),
+      auto_lock_(new AutoSchedulerLock(priority_queue->lock_)),
+      num_pushed_sequences_(0) {
+  DCHECK(CalledOnValidThread());
+}
+
+scoped_ptr<PriorityQueue::Transaction> PriorityQueue::BeginTransaction() {
+  return make_scoped_ptr(new Transaction(this));
+}
+
+bool PriorityQueue::SequenceAndSortKeyPairComparator::operator()(
+    const SequenceAndSortKeyPair& left,
+    const SequenceAndSortKeyPair& right) const {
+  return left.second < right.second;
+}
+
+}  // namespace internal
+}  // namespace base