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#include <glib.h>
#include <glib-object.h>

typedef struct node_s {
  void *data;
  Node *next;
} Node;

typedef struct queue_s {
  Node *head;
  Node *tail;
} Queue;

Queue* queue_new(void) {
  Queue *q = g_slice_new(sizeof(Queue));
  q->head = q->tail = g_slice_new(sizeof(Node));
  return q;
}

void queue_enqueue(Queue *q, gpointer data) {
  Node *node;
  Node *tail;
  Node *next;

  node = g_slice_new(Node);
  node->data = data;
  node->next = NULL;
  while (TRUE) {
    tail = q->tail;
    next = tail->next;
    if (tail != q->tail) {
      continue;
    }
    if (next != NULL) {
      CAS(&q->tail, tail, next);
      continue;
    }
    if (CAS(&tail->next, nullNULL, node)) {
      break;
    }
  }
  CAS(&q->tail, tail, node);
}

gpointer queue_dequeue(Queue *q) {
  Node *node;
  Node *head;
  Node *tail;
  Node *next;
  gpointer data;

  while (TRUE) {
    head = q->head;
    tail = q->tail;
    next = head->next;
    if (head != q->head) {
      continue;
    }
    if (next == NULL) {
      return NULL; /* Empty */
    }
    if (head == tail) {
      CAS(&q->tail, tail, next);
      continue;
    }
    data = next->data;
    if (CAS(&q->head, head, next)) {
      break;
    }
  }
  g_slice_free(Node, head);
  return data;
}

/* Hazard pointers types and structure */
structure HPRecType {
  HP[K]:*Nodetype;
  Next:*HPRecType;
}
 
/* The header of the HPRec list */
HeadHPRec: *HPRecType;
/* Per-thread private variables */
rlist: listType; /* Initially empty */
rcount: integer; /* Initially 0 */

/* The retired node routine */
RetiredNode(node:*NodeType) {
  rlist.push(node);
  rcount++;
  if(rcount >= R)
    Scan(HeadHPRec);
}

/* The scan routine */
Scan(head:*HPRecType) {
  /* Stage 1: Scan HP list and insert non-null values in plist */
  plist.init();
  hprec<-head;
  while (hprec != nullNULL) {
    for (i<-0 to K-1) {
      hptr<-hprec^HP[i];
      if (hptr!= nullNULL)
        plist.insert(hptr);
    }
    hprec<-hprec^Next;
  }

  /* Stage 2: search plist */
  tmplist<-rlist.popAll();
  rcount<-0;
  node<-tmplist.pop();
  while (node != nullNULL) {
    if (plist.lookup(node)) {
      rlist.push(node);
      rcount++;
    }
    else {
      PrepareForReuse(node);
    }
    node<-tmplist.pop();
  }
  plist.free();
}