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      1 // Copyright 2010 the V8 project authors. All rights reserved.
      2 // Redistribution and use in source and binary forms, with or without
      3 // modification, are permitted provided that the following conditions are
      4 // met:
      5 //
      6 //     * Redistributions of source code must retain the above copyright
      7 //       notice, this list of conditions and the following disclaimer.
      8 //     * Redistributions in binary form must reproduce the above
      9 //       copyright notice, this list of conditions and the following
     10 //       disclaimer in the documentation and/or other materials provided
     11 //       with the distribution.
     12 //     * Neither the name of Google Inc. nor the names of its
     13 //       contributors may be used to endorse or promote products derived
     14 //       from this software without specific prior written permission.
     15 //
     16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 
     28 #ifndef V8_UNBOUND_QUEUE_INL_H_
     29 #define V8_UNBOUND_QUEUE_INL_H_
     30 
     31 #include "unbound-queue.h"
     32 
     33 #include "atomicops.h"
     34 
     35 namespace v8 {
     36 namespace internal {
     37 
     38 template<typename Record>
     39 struct UnboundQueue<Record>::Node: public Malloced {
     40   explicit Node(const Record& value)
     41       : value(value), next(NULL) {
     42   }
     43 
     44   Record value;
     45   Node* next;
     46 };
     47 
     48 
     49 template<typename Record>
     50 UnboundQueue<Record>::UnboundQueue() {
     51   first_ = new Node(Record());
     52   divider_ = last_ = reinterpret_cast<AtomicWord>(first_);
     53 }
     54 
     55 
     56 template<typename Record>
     57 UnboundQueue<Record>::~UnboundQueue() {
     58   while (first_ != NULL) DeleteFirst();
     59 }
     60 
     61 
     62 template<typename Record>
     63 void UnboundQueue<Record>::DeleteFirst() {
     64   Node* tmp = first_;
     65   first_ = tmp->next;
     66   delete tmp;
     67 }
     68 
     69 
     70 template<typename Record>
     71 bool UnboundQueue<Record>::Dequeue(Record* rec) {
     72   if (divider_ == Acquire_Load(&last_)) return false;
     73   Node* next = reinterpret_cast<Node*>(divider_)->next;
     74   *rec = next->value;
     75   Release_Store(&divider_, reinterpret_cast<AtomicWord>(next));
     76   return true;
     77 }
     78 
     79 
     80 template<typename Record>
     81 void UnboundQueue<Record>::Enqueue(const Record& rec) {
     82   Node*& next = reinterpret_cast<Node*>(last_)->next;
     83   next = new Node(rec);
     84   Release_Store(&last_, reinterpret_cast<AtomicWord>(next));
     85 
     86   while (first_ != reinterpret_cast<Node*>(Acquire_Load(&divider_))) {
     87     DeleteFirst();
     88   }
     89 }
     90 
     91 
     92 template<typename Record>
     93 bool UnboundQueue<Record>::IsEmpty() const {
     94   return NoBarrier_Load(&divider_) == NoBarrier_Load(&last_);
     95 }
     96 
     97 
     98 template<typename Record>
     99 Record* UnboundQueue<Record>::Peek() const {
    100   if (divider_ == Acquire_Load(&last_)) return NULL;
    101   Node* next = reinterpret_cast<Node*>(divider_)->next;
    102   return &next->value;
    103 }
    104 
    105 } }  // namespace v8::internal
    106 
    107 #endif  // V8_UNBOUND_QUEUE_INL_H_
    108