Add lock-based unbounded queue

src/locked-queue-inl.h

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_LOCKED_QUEUE_INL_
+#define V8_LOCKED_QUEUE_INL_
+
+#include "src/atomic-utils.h"
+#include "src/locked-queue.h"
+
+namespace v8 {
+namespace internal {
+
+template <typename Record>
+struct LockedQueue<Record>::Node : Malloced {
+  Node() : next(nullptr) {}
+  Record value;
+  AtomicValue<Node*> next;
+};
+
+
+template <typename Record>
+inline LockedQueue<Record>::LockedQueue() {
+  head_ = new Node();
+  CHECK(head_ != nullptr);
+  tail_ = head_;
+}
+
+
+template <typename Record>
+inline LockedQueue<Record>::~LockedQueue() {
+  // Destroy all remaining nodes. Note that we do not destroy the actual values.
+  Node* old_node = nullptr;
+  Node* cur_node = head_;
+  while (cur_node != nullptr) {
+    old_node = cur_node;
+    cur_node = cur_node->next.Value();
+    delete old_node;
+  }
+}
+
+
+template <typename Record>
+inline void LockedQueue<Record>::Enqueue(const Record& record) {
+  Node* n = new Node();
+  CHECK(n != nullptr);
+  n->value = record;
+  {
+    base::LockGuard<base::Mutex> guard(&tail_mutex_);
+    tail_->next.SetValue(n);
+    tail_ = n;
+  }
+}
+
+
+template <typename Record>
+inline bool LockedQueue<Record>::Dequeue(Record* record) {
+  Node* old_head = nullptr;
+  {
+    base::LockGuard<base::Mutex> guard(&head_mutex_);
+    old_head = head_;
+    Node* const next_node = head_->next.Value();
+    if (next_node == nullptr) return false;
+    *record = next_node->value;
+    head_ = next_node;
+  }
+  delete old_head;
+  return true;
+}
+
+
+template <typename Record>
+inline bool LockedQueue<Record>::IsEmpty() const {
+  base::LockGuard<base::Mutex> guard(&head_mutex_);
+  return head_->next.Value() == nullptr;
+}
+
+
+template <typename Record>
+inline bool LockedQueue<Record>::Peek(Record* record) const {
+  base::LockGuard<base::Mutex> guard(&head_mutex_);
+  Node* const next_node = head_->next.Value();
+  if (next_node == nullptr) return false;
+  *record = next_node->value;
+  return true;
+}
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_LOCKED_QUEUE_INL_