#if !defined(_DATAQ_H_)

#define _DATAQ_H_ 1

#include "mylock.h"

typedef struct _data_item {
    struct _data_item* next;
} data_item_t;

typedef int (*data_item_match_fn_t)(data_item_t*);
/* like data_item_match_fn_t, plus a caller-owned per-scan context */
typedef int (*data_item_match_ctx_fn_t)(data_item_t*, void*);
typedef void (*data_item_killer_t)(data_item_t*);

typedef struct {
    data_item_t*       head;
    data_item_t*       tail;
    data_item_killer_t killer;
    mylock_t           lock;
} dataq_t;

#define DATAQ_EMPTY(q) ((q)->head == NULL)

extern int          dataq_init(dataq_t*, data_item_killer_t);
extern data_item_t* dataq_deq(dataq_t*, data_item_match_fn_t);
/* bug-1864: first item matching f, with ctx passed to every f call of this
 * one scan (under the queue lock) -- lets a matcher remember what it saw
 * earlier in the same scan */
extern data_item_t* dataq_deq_ctx(dataq_t*, data_item_match_ctx_fn_t, void*);
extern int          dataq_enq(dataq_t*, data_item_t*);
extern void         dataq_fini(dataq_t*);

#endif