#ifndef FIFO_H
#define FIFO_H
#include "brttypes.h"

struct fifo_entry {
    unsigned int keylen;
    unsigned int vallen;
    unsigned char type;
    TXNID xid;
    unsigned char key[];
};

typedef struct fifo *FIFO;

int toku_fifo_create(FIFO *);
void toku_fifo_free(FIFO *);
int toku_fifo_n_entries(FIFO);
int toku_fifo_enq_cmdstruct (FIFO fifo, const BRT_CMD cmd);
int toku_fifo_enq (FIFO, const void *key, ITEMLEN keylen, const void *data, ITEMLEN datalen, int type, TXNID xid);
int toku_fifo_peek (FIFO, bytevec *key, ITEMLEN *keylen, bytevec *data, ITEMLEN *datalen, u_int32_t *type, TXNID *xid);
int toku_fifo_peek_cmdstruct (FIFO, BRT_CMD, DBT*, DBT*); // fill in the BRT_CMD, using the two DBTs for the DBT part.
int toku_fifo_deq(FIFO);

unsigned long toku_fifo_memory_size(FIFO); // return how much memory the fifo uses.

//These two are problematic, since I don't want to malloc() the bytevecs, but dequeueing the fifo frees the memory.
//int toku_fifo_peek_deq (FIFO, bytevec *key, ITEMLEN *keylen, bytevec *data, ITEMLEN *datalen, u_int32_t *type, TXNID *xid);
//int toku_fifo_peek_deq_cmdstruct (FIFO, BRT_CMD, DBT*, DBT*); // fill in the BRT_CMD, using the two DBTs for the DBT part.
void toku_fifo_iterate (FIFO, void(*f)(bytevec key,ITEMLEN keylen,bytevec data,ITEMLEN datalen,int type, TXNID xid, void*), void*);

#define FIFO_ITERATE(fifo,keyvar,keylenvar,datavar,datalenvar,typevar,xidvar,body) ({      \
  int fifo_iterate_off;                                                                    \
  for (fifo_iterate_off = toku_fifo_iterate_internal_start(fifo);                          \
       toku_fifo_iterate_internal_has_more(fifo, fifo_iterate_off);			   \
       fifo_iterate_off = toku_fifo_iterate_internal_next(fifo, fifo_iterate_off)) {       \
      struct fifo_entry *e = toku_fifo_iterate_internal_get_entry(fifo, fifo_iterate_off); \
      bytevec keyvar = e->key;                                                             \
      ITEMLEN keylenvar = e->keylen;                                                       \
      bytevec datavar = e->key + e->keylen;                                           \
      ITEMLEN datalenvar = e->vallen;                                                 \
      int     typevar = e->type;                                                      \
      TXNID   xidvar = e->xid;                                                        \
      body;                                                                           \
  } })

// Internal functions for the iterator.
int toku_fifo_iterate_internal_start(FIFO fifo);
int toku_fifo_iterate_internal_has_more(FIFO fifo, int off);
int toku_fifo_iterate_internal_next(FIFO fifo, int off);
struct fifo_entry * toku_fifo_iterate_internal_get_entry(FIFO fifo, int off);


#endif