src/circular-queue-inl.h

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#ifndef V8_CIRCULAR_BUFFER_INL_H_
#define V8_CIRCULAR_BUFFER_INL_H_

#include "circular-queue.h"

namespace v8 {
namespace internal {


template<typename Record>
CircularQueue<Record>::CircularQueue(int desired_buffer_size_in_bytes)
    : buffer_(NewArray<Record>(desired_buffer_size_in_bytes / sizeof(Record))),
      buffer_end_(buffer_ + desired_buffer_size_in_bytes / sizeof(Record)),
      enqueue_semaphore_(
          OS::CreateSemaphore(static_cast<int>(buffer_end_ - buffer_) - 1)),
      enqueue_pos_(buffer_),
      dequeue_pos_(buffer_) {
  // To be able to distinguish between a full and an empty queue
  // state, the queue must be capable of containing at least 2
  // records.
  ASSERT((buffer_end_ - buffer_) >= 2);
}


template<typename Record>
CircularQueue<Record>::~CircularQueue() {
  DeleteArray(buffer_);
  delete enqueue_semaphore_;
}


template<typename Record>
void CircularQueue<Record>::Dequeue(Record* rec) {
  ASSERT(!IsEmpty());
  *rec = *dequeue_pos_;
  dequeue_pos_ = Next(dequeue_pos_);
  // Tell we have a spare record.
  enqueue_semaphore_->Signal();
}


template<typename Record>
void CircularQueue<Record>::Enqueue(const Record& rec) {
  // Wait until we have at least one spare record.
  enqueue_semaphore_->Wait();
  ASSERT(Next(enqueue_pos_) != dequeue_pos_);
  *enqueue_pos_ = rec;
  enqueue_pos_ = Next(enqueue_pos_);
}


template<typename Record>
Record* CircularQueue<Record>::Next(Record* curr) {
  return ++curr != buffer_end_ ? curr : buffer_;
}


void* SamplingCircularQueue::Enqueue() {
  WrapPositionIfNeeded(&producer_pos_->enqueue_pos);
  void* result = producer_pos_->enqueue_pos;
  producer_pos_->enqueue_pos += record_size_;
  return result;
}


void SamplingCircularQueue::WrapPositionIfNeeded(
    SamplingCircularQueue::Cell** pos) {
  if (**pos == kEnd) *pos = buffer_;
}


} }  // namespace v8::internal

#endif  // V8_CIRCULAR_BUFFER_INL_H_